* [PATCH bpf-next v4 00/16] Redesign Verification Errors
@ 2026-08-12 23:33 Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers Kumar Kartikeya Dwivedi
` (16 more replies)
0 siblings, 17 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
TL;DR: This set reworks verifier error messages to include source and
instruction annotations, together with more causal context, making
failures easier to understand and more actionable when debugging and
repairing BPF programs.
Changelog:
----------
v3 -> v4
v3: https://lore.kernel.org/bpf/20260713153910.2556007-1-memxor@gmail.com
* Introduce helpers with their first callers and add printf annotations.
(Eduard, Sashiko)
* Remove "report" from diagnostic function names. (Sashiko)
* Reuse bpf_linfo_source and seq_buf, simplify internal names, and use shared
formatting storage. (Eduard)
* Use compact common event fields and record branches at successor entry.
(Eduard)
* Bound event storage at 1 MiB, use kvrealloc(), and drop events non-fatally.
(Eduard, Sashiko)
* Restore diagnostic history only for activated queued states, preserving the
active failure trace during cleanup. (Eduard, Sashiko)
* Record register changes through begin/end and scrub helpers, deriving targets
and origins without caller-saved snapshots. (Eduard)
* Store lineage marks on events and rewind shared formatting storage after
rendering each event. (Eduard)
* Record iterator return values before snapshotting alternate paths. (Sashiko)
* Use the current verifier instruction for global-subprogram dynptr errors.
(Sashiko)
* Use the supplied call name for nullable global-subprogram arguments.
(Sashiko)
* Describe global calls under locks as a verifier restriction rather than a
sleepability failure. (Sashiko)
* Keep diagnostic strings unsplit and put long call openings on their own
line. (Eduard)
* Keep kfunc metadata zeroed before early fetch and allowability failures.
(Sashiko)
* Drop the Verifier Internal Error report patch. (Eduard)
* Distinguish never-initialized registers from invalidated registers.
(local review)
* Preserve the legacy different-lock verifier message. (local review)
* Preserve nullable type qualifiers and stable mismatch formatting.
(local review)
* Mark truncated call chains with an ellipsis. (local review)
v2 -> v3
v2: https://lore.kernel.org/bpf/20260619205934.1312876-1-memxor@gmail.com
* Address various comments from Eduard and Sashiko.
* Move instruction context from a separate gutter into a new section
following source context, since surrounding source lines and BPF
instructions do not map one-to-one.
* Fix active-path branch reconstruction when switching to queued states,
and expand register histories to follow value lineage across spills,
fills, stack reads, helper/kfunc clobbers, and dynptr invalidation.
* Misc improvements and refinements.
v1 -> v2
v1: https://lore.kernel.org/bpf/20260605063412.974640-1-memxor@gmail.com
* Reworked diagnostic history from per-verifier-state log to active
path log with positions saved and reset when verifier search
backtracks. (Eduard)
* Moved reusable diagnostic formatting storage into struct bpf_diag
under struct bpf_verifier_env, and removed large per-report scratch
buffers from verifier stack frames. (Eduard)
* Added stack-slot events so diagnostics follow ordinary stack
spill/fill value flow and invalidations in register-scoped
histories. (Eduard)
* Reused existing source and BTF formatting helpers for diagnostics,
including bpf_get_linfo_file_line() and
btf_type_snprintf_show_name(). (Eduard)
* Fixed diagnostic edge cases around signed offset text,
BPF_MAX_VAR_OFF reporting, negative-offset clamping, poisoned
stack reads, and borrowed-reference invalidations. (Eduard)
* Fixed various miscellaneous diagnostic bugs. (Sashiko)
* Misc improvements and refinements.
--
Motivation
~~~~~~~~~~
The verifier log is the primary interface through which the verifier
communicates to the user its verdict on whether a program was accepted
or rejected.
To aid the debugging of rejection decisions, the verifier also reports
the symbolic state of the program at each instruction, across every explored
path of the BPF program. Such detailed information is critical to
introspect the correctness of verification decisions, and provide
insight into why a given program may have failed to load in the kernel.
A constant pain point in the BPF ecosystem throughout the years has
been the difficulty of debugging verification errors. The human-readable error
messages produced in response to a failure in satisfying safety-related
constraints are often terse, context-dependent, or insufficient for
understanding why a given error may have happened. Users must fall back
to the verbose instruction-by-instruction breakdown of how the symbolic
state evolved to surface the root cause. For programs with a huge log
volume due to high verification complexity, such logs quickly become
inscrutable.
All of this has made life difficult for users lacking an understanding
of how the verifier works, and the various heuristics and idiosyncrasies
used by it. In some cases, even seasoned BPF experts spend significant
time reverse engineering why a program may have failed, and have to
reach into the verifier's source code to form a complete picture of the
verification process.
Such a steep learning curve and cognitive burden also hurts the speed of
BPF development, as the verifier sits right in the middle of the user's
iteration loop while they make use of BPF to solve any given problem.
Expertise in debugging verifier errors does not scale in terms of teams
deploying these programs in production across a diverse set of kernels.
Overall, this leads to a poorer developer experience, causes visible
user dissatisfaction, and remains a drag on wider BPF adoption. With
some of the more recent developments where users increasingly leverage
AI tooling [0] to author their code, this bottleneck becomes even more
critical to address, since it throttles the much faster iteration loop
of AI agents.
[0]: https://lwn.net/Articles/1075067
Approach
~~~~~~~~
This series starts moving selected failures from terse terminal messages
toward diagnostics that carry the relevant context for a verification
failure. The existing verbose log remains the low-level trace. For selected
failures, the new report is emitted after this trace and answers the
immediate debugging questions:
- what verifier rule failed,
- why the current state does not satisfy it,
- where the failing instruction maps to source,
- which earlier branch or state event made this path fail,
- what kind of source change would satisfy the verifier.
The series adds a text-only diagnostics framework under kernel/bpf and
uses it to augment selected verifier errors. Existing verbose(env, ...)
messages are kept, so current selftest expectations and existing log
consumers continue to see the legacy text. The new report has a uniform
outer shape:
Verification failed: <category>: <problem>
Reason:
exact reason for the verification failure, with details
At:
source and instruction annotation
Causal path:
compressed branch and verifier-state events relevant for debugging
Suggestion:
speculation on potential fixes to repair the program
The outer shape is shared, but report construction is category-specific.
The categories are intentionally broad and reviewable. This revision
covers representative cases in Register Type Safety, Memory Safety,
Resource Lifetime Safety, Call Type Safety, Execution Context Safety,
Program Structure, Policy, and Verifier Limit errors.
It does not attempt to convert every verbose(env, ...) site for now.
Additional verbose-only errors can be moved into the same framework
incrementally.
The following excerpts are copied from this current run on this branch:
./test_progs -j1 \
-a cpumask/test_populate_invalid_destination,\
cpumask/test_alloc_no_release,\
verifier_helper_value_access/via_variable_no_max_check_1,\
verifier_sock/invalidate_pkt_pointers_from_global_func \
-vv
They show the old terminal error and the exact new diagnostic report,
including the source and instruction annotations.
Call Type Safety, cpumask/test_populate_invalid_destination:
Legacy:
R1 type=scalar expected=fp
Diagnostic:
Verification failed: Call Type Safety: Invalid call argument
Reason:
The first argument (R1) to bpf_cpumask_populate does not satisfy the verifier contract: the kfunc
expects 24 bytes of memory for (struct bpf_cpumask), but it is an integer scalar and not
verifier-known memory.
At:
test_populate_invalid_destination @ cpumask_failure.c:234:8
Source context:
232 | ...
233 | ...
>>> 234 | ret = bpf_cpumask_populate(invalid, &bits, sizeof(bits));
| ^-- error: invalid first argument (R1) for bpf_cpumask_populate
235 | if (!ret)
236 | err = 2;
Instruction context:
2 | (b7) r1 = 1193046
3 | (b7) r3 = 8
>>> 4 | (85) call bpf_cpumask_populate#62860
5 | (56) if w0 != 0x0 goto pc+4
6 | (18) r1 = 0xffffc9000028e000
Causal path:
test_populate_invalid_destination @ cpumask_failure.c:234:8
Source context:
232 | ...
233 | ...
>>> 234 | ret = bpf_cpumask_populate(invalid, &bits, sizeof(bits));
| ^-- update: R1 changed from context pointer at offset 0 to integer scalar value
| 1193046
235 | if (!ret)
236 | err = 2;
Instruction context:
0 | (bf) r2 = r10
1 | (07) r2 += -8
>>> 2 | (b7) r1 = 1193046
3 | (b7) r3 = 8
4 | (85) call bpf_cpumask_populate#62860
Suggestion:
Pass stack, map, context, or other verifier-known memory of the expected type and size, not an
integer cast to a pointer.
Register Type Safety, verifier_sock/invalidate_pkt_pointers_from_global_func:
Legacy:
R7 invalid mem access 'scalar'
Diagnostic:
Verification failed: Register Type Safety: Invalid dereference
Reason:
R7 is an integer scalar here, not a pointer to memory.
At:
invalidate_pkt_pointers_from_global_func @ verifier_sock.c:1067:5
Source context:
1065 | ...
1066 | skb_pull_data1(sk, 0);
>>> 1067 | *p = 42; /* this is unsafe */
| ^-- error: invalid dereference of R7 (an integer scalar)
1068 | ...
1069 | }
Instruction context:
8 | (85) call pc+4
9 | (b4) w1 = 42
>>> 10 | (63) *(u32 *)(r7 +0) = r1
11 | (bc) w0 = w6
12 | (95) exit
Causal path:
invalidate_pkt_pointers_from_global_func @ verifier_sock.c:1062:29
Source context:
1060 | int invalidate_pkt_pointers_from_global_func(struct __sk_buff *sk)
1061 | ...
>>> 1062 | int *p = (void *)(long)sk->data;
| ^-- update: R7 changed from uninitialized value to pkt at offset 0
1063 | ...
1064 | if ((void *)(p + 1) > (void *)(long)sk->data_end)
Instruction context:
0 | (b4) w6 = 2
1 | (61) r2 = *(u32 *)(r1 +80)
>>> 2 | (61) r7 = *(u32 *)(r1 +76)
3 | (bf) r3 = r7
4 | (07) r3 += 4
invalidate_pkt_pointers_from_global_func @ verifier_sock.c:1064:22
Source context:
1062 | int *p = (void *)(long)sk->data;
1063 | ...
>>> 1064 | if ((void *)(p + 1) > (void *)(long)sk->data_end)
| ^-- branch: took the false branch of this conditional, goto not followed
1065 | ...
1066 | skb_pull_data1(sk, 0);
Instruction context:
3 | (bf) r3 = r7
4 | (07) r3 += 4
>>> 5 | (2d) if r3 > r2 goto pc+5
6 | (b4) w6 = 0
7 | (b4) w2 = 0
invalidate_pkt_pointers_from_global_func @ verifier_sock.c:1066:2
Source context:
1064 | if ((void *)(p + 1) > (void *)(long)sk->data_end)
1065 | ...
>>> 1066 | skb_pull_data1(sk, 0);
| ^-- invalidated: R7: packet data may have moved; previous value was pkt at
| offset 0
1067 | *p = 42; /* this is unsafe */
1068 | ...
Instruction context:
6 | (b4) w6 = 0
7 | (b4) w2 = 0
>>> 8 | (85) call pc+4
9 | (b4) w1 = 42
10 | (63) *(u32 *)(r7 +0) = r1
Suggestion:
Preserve a pointer-valued register where needed, or reload and revalidate the pointer after scalar
arithmetic, helper calls, or other operations that can invalidate it.
Memory Safety, verifier_helper_value_access/via_variable_no_max_check_1:
Legacy:
R1 unbounded memory access, make sure to bounds check any such access
Diagnostic:
Verification failed: Memory Safety: Access outside bounds
Reason:
The verifier cannot prove offset + access_size <= object_size. Here, the maximal bound for a
memory access is 4294967295 and exceeds maximum allowed offset of 536870912. R1 is map_value;
offset is variable: known bits 0x0, unknown mask 0xffffffff; signed range [0, 4294967295],
unsigned range [0, 4294967295]; access_size is 1; object_size is 48.
At:
via_variable_no_max_check_1 @ verifier_helper_value_access.c:627:2
Source context:
625 | ...
626 | ...
>>> 627 | asm volatile (" \
| ^-- error: access may be outside object bounds
628 | ...
629 | ...
Instruction context:
11 | (b7) r2 = 1
12 | (b7) r3 = 0
>>> 13 | (85) call bpf_probe_read_kernel#113
14 | (95) exit
Causal path:
via_variable_no_max_check_1 @ verifier_helper_value_access.c:627:2
Source context:
625 | ...
626 | ...
>>> 627 | asm volatile (" \
| ^-- update: R0 changed from uninitialized value to nullable map value from
| map_hash_48b at offset 0
628 | ...
629 | ...
Instruction context:
4 | (18) r1 = 0xffff88810a3ea000
>>> 6 | (85) call bpf_map_lookup_elem#1
7 | (15) if r0 == 0x0 goto pc+6
8 | (bf) r1 = r0
via_variable_no_max_check_1 @ verifier_helper_value_access.c:627:2
Source context:
625 | ...
626 | ...
>>> 627 | asm volatile (" \
| ^-- branch: took the false branch of this conditional, goto not followed
628 | ...
629 | ...
Instruction context:
6 | (85) call bpf_map_lookup_elem#1
>>> 7 | (15) if r0 == 0x0 goto pc+6
8 | (bf) r1 = r0
9 | (61) r3 = *(u32 *)(r0 +0)
via_variable_no_max_check_1 @ verifier_helper_value_access.c:627:2
Source context:
625 | ...
626 | ...
>>> 627 | asm volatile (" \
| ^-- update: R1 changed from uninitialized value to map value from map_hash_48b
| at offset 0
628 | ...
629 | ...
Instruction context:
6 | (85) call bpf_map_lookup_elem#1
7 | (15) if r0 == 0x0 goto pc+6
>>> 8 | (bf) r1 = r0
9 | (61) r3 = *(u32 *)(r0 +0)
10 | (0f) r1 += r3
via_variable_no_max_check_1 @ verifier_helper_value_access.c:627:2
Source context:
625 | ...
626 | ...
>>> 627 | asm volatile (" \
| ^-- update: R1 changed from map value from map_hash_48b at offset 0 to map value
| from map_hash_48b with variable offset: known bits 0x0, unknown mask
| 0xffffffff, signed range [0, 4294967295], unsigned range [0, 4294967295]
628 | ...
629 | ...
Instruction context:
8 | (bf) r1 = r0
9 | (61) r3 = *(u32 *)(r0 +0)
>>> 10 | (0f) r1 += r3
11 | (b7) r2 = 1
12 | (b7) r3 = 0
Suggestion:
Add or adjust a bounds check that proves offset + access_size stays within the object.
Resource Lifetime Safety, cpumask/test_alloc_no_release:
Legacy:
Unreleased reference id=2 alloc_insn=0
BPF_EXIT instruction in main prog would lead to reference leak
Diagnostic:
Verification failed: Resource Lifetime Safety: Unreleased resource
Reason:
Owned resource (id=2) was acquired at instruction 0 and still needs to be released before this
exit path.
At:
test_alloc_no_release @ cpumask_failure.c:36:5
Source context:
34 | ...
35 | ...
>>> 36 | int BPF_PROG(test_alloc_no_release, struct task_struct *task, u64 clone_flags)
| ^-- error: owned resource (id=2) still needs release
37 | ...
38 | ...
Instruction context:
19 | (7b) *(u64 *)(r10 -8) = r6
20 | (b4) w0 = 0
>>> 21 | (95) exit
Causal path:
test_alloc_no_release @ cpumask_common.h:78:12
Source context:
76 | ...
77 | ...
>>> 78 | cpumask = bpf_cpumask_create();
| ^-- acquired: owned resource (id=2)
79 | if (!cpumask) {
80 | err = 1;
Instruction context:
>>> 0 | (85) call bpf_cpumask_create#62851
1 | (bf) r6 = r0
2 | (55) if r6 != 0x0 goto pc+5
test_alloc_no_release @ cpumask_common.h:79:6
Source context:
77 | ...
78 | cpumask = bpf_cpumask_create();
>>> 79 | if (!cpumask) {
| ^-- branch: took the true branch of this conditional, goto followed
80 | err = 1;
81 | ...
Instruction context:
0 | (85) call bpf_cpumask_create#62851
1 | (bf) r6 = r0
>>> 2 | (55) if r6 != 0x0 goto pc+5
3 | (18) r1 = 0xffffc90000252000
test_alloc_no_release @ cpumask_common.h:84:6
Source context:
82 | ...
83 | ...
>>> 84 | if (!bpf_cpumask_empty(cast(cpumask))) {
| ^-- branch: took the true branch of this conditional, goto followed
85 | err = 2;
86 | bpf_cpumask_release(cpumask);
Instruction context:
9 | (85) call bpf_cpumask_empty#62852
10 | (54) w0 &= 1
>>> 11 | (56) if w0 != 0x0 goto pc+7
12 | (18) r1 = 0xffffc90000252000
Suggestion:
Release or transfer ownership of the acquired resource on every path before the program exits.
Patch layout:
- Patches 1-2 add the common infrastructure: report sections, diagnostic
categories, source-line lookup, and separate source and instruction
context blocks.
- Patches 3-7 add growable environment-owned diagnostic history. The
history follows the active verifier path and is pruned when
backtracking; it records branch outcomes, material register changes,
reference lifetime events, and execution-context events so reports can
explain the path and causal state transitions that led to the failure.
- Patches 8-15 add the first category-specific reports. These patches
hook selected verifier failure sites and choose the evidence that is
useful for that error class.
- Patch 16 gates diagnostic collection and rendering on verifier log
level, so stats-only loads do not collect the extra path history.
The overhead is limited to verbose log mode through this change.
Evaluation
~~~~~~~~~~
To quantitatively assess diagnostic quality beyond subjective human
feedback, we use AI models (called over APIs) and veristat metrics to
compare results.
Models are used as a way to measure repair utility of the extra
diagnostics over a fixed test set. Each prompt contains only a sanitized
source snippet and either the legacy verifier log or the new diagnostic
log. To avoid leaking the answer through the test itself, comments,
annotations, and other source hints that describe the intended failure
were removed. The model is not given internet access, repository access,
test execution, verifier access, or the expected fix. The expected
causes and intended repairs are kept outside the prompt. Under those
constraints, correctness, exact repair rate, output size, reasoning
tokens, cost, and wall time provide a proxy for whether the additional
verifier context makes the failure easier to understand and turn into a
source-level fix.
Verifier cost is assessed by forcing the collection of diagnostics
information during normal verification. By default, this information is
collected and processed only when verbose logs are enabled, but forcing
it even without a verbose log helps us measure the CPU time and memory
cost of the extra data.
Both evaluations are covered in the sections below.
Repair Quality
--------------
Repair quality is measured by asking API-only models to propose source
fixes from a sanitized source snippet and verifier log. The criterion is
score >= 3 on a 0-4 local grading scale, where 3 means a likely fix with
incomplete detail and 4 means an actionable source-level fix. Score 4 is
reported separately as the exact repair rate. The reported model set
contains 596 completed API responses: 298 diagnostic and 298 legacy.
Main results (details available in Appendix):
Metric Diagnostic Legacy Delta
---------------------------------- ----------- ----------- --------
Answers 298 298
Success rate 97.0% 97.3% -0.3 pp
Exact repair rate 82.2% 72.1% +10.1 pp
Mean score 3.79 3.69 +0.10
Solver cost $8.93 $10.37 -13.8%
Mean output tokens per answer 1662 1975 -15.8%
Mean reasoning tokens per answer 951 1080 -11.9%
Mean wall time per answer 37.3s 44.1s -15.4%
Diagnostic prompts carry more input context. The resulting answers are
still shorter and cheaper. In this run, diagnostics do not materially
change the coarse success rate, but they increase exact repairs by 10.1
percentage points while reducing cost, output tokens, reasoning tokens,
and wall time.
Verifier cost
-------------
Verifier cost is measured with veristat over the BPF selftest programs
selected by tools/testing/selftests/bpf/veristat.cfg, with five
repetitions per configuration. With diagnostics gated by log level, wall
time and verifier duration stay close to baseline. Forcing diagnostics
on for every verifier run adds modest overhead on this workload.
memory.peak is measured with cgroup v2 memory accounting for each
program load. The table reports the mean wall time, the mean summed
verifier duration, and the mean of the per-repetition maximum
memory.peak values.
Configuration Wall time mean Verifier duration memory.peak
---------------------------- -------------- ----------------- -----------
bpf-next baseline 25.78s 9.86s 142 MiB
diagnostics, gated 26.64s 10.16s 144 MiB
diagnostics, forced on 28.01s 11.00s 148 MiB
TODO
~~~~
Known follow-up work:
- Convert more verbose-only verifier errors into category-specific
reports.
- Integrate loop-convergence failure summarization from Eduard.
- Report candidate kfuncs/helpers for releasing owned resources.
- Explore association of source variables with verifier registers
where debug info permits it.
- Refine suggestions per category and, where useful, link diagnostics
to maintained documentation.
- Bring verifier warnings into the same reporting framework.
Appendix: AI repair details
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 20 verifier-failing selftest cases are:
Case Diff Category Selftest selector
------- ------ -------------------------- ---------------------------------------------
case-001 easy Call Type Safety cpumask/test_populate_invalid_destination
case-002 easy Resource Lifetime Safety cpumask/test_alloc_no_release
case-003 easy Register Type Safety verifier_spill_fill/check_corrupted_spill_fill
case-004 easy Register Type Safety test_global_funcs/global_func12
case-005 easy Execution Context Safety preempt_lock/preempt_sleepable_helper
case-006 easy Policy verifier_helper_restricted/in_bpf_prog_type_kprobe_1
case-007 medium Memory Safety dynptr/dynptr_slice_var_len1
case-008 medium Call Type Safety dynptr/test_dynptr_skb_small_buff
case-009 medium Call Type Safety task_kfunc/task_kfunc_acquire_untrusted
case-010 medium Register Type Safety test_global_funcs/global_func6
case-011 medium Resource Lifetime Safety dynptr/ringbuf_missing_release2
case-012 medium Execution Context Safety irq/irq_sleepable_helper_global_subprog
case-013 medium Verifier Limit test_global_funcs/global_func1
case-014 hard Memory Safety verifier_helper_value_access/via_variable_no_max_check_1
case-015 hard Register Type Safety verifier_sock/invalidate_pkt_pointers_from_global_func
case-016 hard Resource Lifetime Safety verifier_ref_tracking/check_free_in_one_subbranch
case-017 hard Resource Lifetime Safety irq/irq_restore_ooo
case-018 hard Resource Lifetime Safety res_spin_lock_failure/res_spin_lock_ooo_unlock
case-019 hard Program Structure verifier_loops1/bounded_recursion
case-020 hard Verifier Limit verifier_liveness_exp/liveness_exponential_complexity
The grading scale is:
- 4: identifies the verifier cause and gives an actionable source-level fix.
- 3: gives a likely fix, but with incomplete explanation or detail.
- 2: identifies part of the issue, but not enough to fix confidently.
- 1: gives only a broad verifier-area answer, or a wrong/insufficient fix.
- 0: does not identify the intended verifier failure.
Detailed effort metrics for the model set:
Metric Variant Mean Median P99
----------------------- ---------- -------- -------- --------
Cost per answer diagnostic $0.030 $0.019 $0.203
Cost per answer legacy $0.035 $0.018 $0.223
Input tokens diagnostic 1391 1220 4048
Input tokens legacy 1052 805 3655
Output tokens diagnostic 1662 954 8680
Output tokens legacy 1975 1034 9912
Reasoning tokens diagnostic 951 208 8108
Reasoning tokens legacy 1080 228 6322
Wall time diagnostic 37.3s 18.3s 222.7s
Wall time legacy 44.1s 19.8s 255.5s
Per-model results for diagnostic prompts:
Model profile Ans Succ Exact Mean Cost OutK ReasK Wall
----------------------------------------- --- ----- ----- ---- ------- ---- ----- -----
anthropic-haiku-4.5-default 20 90.0 80.0 3.70 $0.087 11.4 0.0 5.0s
anthropic-opus-4.8-high 20 100.0 90.0 3.90 $0.819 25.5 0.0 15.5s
anthropic-opus-4.8-medium 20 95.0 90.0 3.85 $0.870 27.5 0.0 12.7s
anthropic-sonnet-4.6-high 20 95.0 80.0 3.75 $0.824 48.9 0.0 21.6s
anthropic-sonnet-4.6-medium 20 100.0 65.0 3.65 $0.278 12.4 0.0 6.6s
openai-gpt-5.3-codex-high 20 100.0 80.0 3.80 $0.601 39.8 33.9 25.0s
openai-gpt-5.3-codex-medium 20 95.0 85.0 3.80 $0.287 17.5 11.4 13.5s
openai-gpt-5.5-high 20 100.0 90.0 3.90 $2.356 74.4 65.2 56.8s
openai-gpt-5.5-low 20 100.0 90.0 3.90 $0.686 18.7 8.5 21.3s
openai-gpt-5.5-medium 19 100.0 84.2 3.84 $1.353 41.1 31.8 37.4s
openai-gpt-5.5-none 20 95.0 90.0 3.85 $0.457 11.1 0.0 10.4s
openrouter-deepseek-r1-0528 20 100.0 75.0 3.75 $0.145 61.5 53.8 98.3s
openrouter-deepseek-v3.2 19 100.0 78.9 3.79 $0.028 64.2 58.1 87.3s
openrouter-glm-5.1-high 20 95.0 80.0 3.75 $0.113 28.8 20.7 19.3s
openrouter-qwen3-coder 20 90.0 75.0 3.65 $0.028 12.4 0.0 7.1s
Per-model results for legacy prompts:
Model profile Ans Succ Exact Mean Cost OutK ReasK Wall
----------------------------------------- --- ----- ----- ---- ------- ---- ----- -----
anthropic-haiku-4.5-default 20 90.0 45.0 3.35 $0.081 11.6 0.0 5.0s
anthropic-opus-4.8-high 20 90.0 70.0 3.60 $1.192 42.2 0.0 17.5s
anthropic-opus-4.8-medium 20 95.0 85.0 3.80 $1.001 34.5 0.0 13.4s
anthropic-sonnet-4.6-high 20 100.0 75.0 3.75 $1.181 74.1 0.0 24.4s
anthropic-sonnet-4.6-medium 20 95.0 65.0 3.60 $0.420 23.4 0.0 12.3s
openai-gpt-5.3-codex-high 20 100.0 85.0 3.85 $0.562 37.8 31.6 27.1s
openai-gpt-5.3-codex-medium 20 100.0 75.0 3.75 $0.318 20.3 13.7 13.6s
openai-gpt-5.5-high 19 100.0 78.9 3.79 $2.613 84.0 75.4 98.1s
openai-gpt-5.5-low 20 100.0 75.0 3.75 $0.664 19.0 9.7 21.7s
openai-gpt-5.5-medium 20 100.0 75.0 3.75 $1.602 50.2 41.0 56.1s
openai-gpt-5.5-none 20 95.0 85.0 3.80 $0.416 10.7 0.0 10.9s
openrouter-deepseek-r1-0528 20 95.0 70.0 3.65 $0.149 64.6 57.5 92.5s
openrouter-deepseek-v3.2 20 100.0 60.0 3.60 $0.030 74.3 67.8 98.3s
openrouter-glm-5.1-high 19 100.0 63.2 3.63 $0.115 32.1 24.9 30.4s
openrouter-qwen3-coder 20 100.0 75.0 3.75 $0.022 9.5 0.0 5.4s
Kumar Kartikeya Dwivedi (16):
bpf: Add verifier diagnostics report helpers
bpf: Add source and instruction diagnostic context
bpf: Add verifier diagnostic event log
bpf: Prune verifier diagnostics when switching paths
bpf: Track verifier register diagnostic events
bpf: Track verifier reference diagnostic events
bpf: Track verifier context diagnostic events
bpf: Report Register Type Safety errors
bpf: Report Memory Safety bounds errors
bpf: Report Resource Lifetime reference leaks
bpf: Report Call Type Safety argument errors
bpf: Report Execution Context Safety errors
bpf: Report Program Structure CFG errors
bpf: Report Policy helper and kfunc errors
bpf: Report Verifier Limit errors
bpf: Gate verifier diagnostics on log level
include/linux/bpf.h | 13 +-
include/linux/bpf_verifier.h | 16 +
include/linux/btf.h | 1 +
kernel/bpf/Makefile | 2 +-
kernel/bpf/btf.c | 10 +
kernel/bpf/cfg.c | 35 +
kernel/bpf/core.c | 35 +-
kernel/bpf/diagnostics.c | 2319 +++++++++++++++++
kernel/bpf/diagnostics.h | 177 ++
kernel/bpf/liveness.c | 6 +
kernel/bpf/log.c | 11 -
kernel/bpf/verifier.c | 1106 +++++++-
.../bpf/progs/test_global_func_deep_stack.c | 1 +
.../selftests/bpf/progs/verifier_map_in_map.c | 1 +
.../selftests/bpf/progs/verifier_uninit.c | 1 +
15 files changed, 3582 insertions(+), 152 deletions(-)
create mode 100644 kernel/bpf/diagnostics.c
create mode 100644 kernel/bpf/diagnostics.h
base-commit: 3a59f11e0f989bdd637c87151992605a6559a7cb
--
2.53.0
^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:41 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context Kumar Kartikeya Dwivedi
` (15 subsequent siblings)
16 siblings, 1 reply; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Add a small diagnostics renderer for verifier reports and wire it into
the BPF build. The initial helpers emit the common text structure: a
failure header plus reusable report sections.
Wrap report prose at 100 columns so Reason and Suggestion text stays
readable without changing source or instruction gutters.
Gate the helpers on normal verifier log output from the start, so
BPF_LOG_STATS-only loads do not collect or render diagnostics.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/Makefile | 2 +-
kernel/bpf/diagnostics.c | 55 ++++++++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 16 ++++++++++++
3 files changed, 72 insertions(+), 1 deletion(-)
create mode 100644 kernel/bpf/diagnostics.c
create mode 100644 kernel/bpf/diagnostics.h
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 4dc41bf5780c..90255d80e5be 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -6,7 +6,7 @@ cflags-nogcse-$(CONFIG_X86)$(CONFIG_CC_IS_GCC) := -fno-gcse
endif
CFLAGS_core.o += -Wno-override-init $(cflags-nogcse-yy)
-obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o cnum.o log.o token.o liveness.o const_fold.o
+obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o cnum.o log.o token.o liveness.o const_fold.o diagnostics.o
obj-$(CONFIG_BPF_SYSCALL) += bpf_iter.o map_iter.o task_iter.o prog_iter.o link_iter.o
obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o bloom_filter.o
obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o bpf_insn_array.o
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
new file mode 100644
index 000000000000..ba57aabd399f
--- /dev/null
+++ b/kernel/bpf/diagnostics.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2026 Meta Platforms, Inc. and affiliates.
+
+#include <linux/bpf_verifier.h>
+#include <linux/ctype.h>
+#include <linux/stdarg.h>
+
+#include "diagnostics.h"
+
+#define MEMORY_SAFETY "Memory Safety"
+#define REGISTER_TYPE_SAFETY "Register Type Safety"
+#define CALL_TYPE_SAFETY "Call Type Safety"
+#define RESOURCE_LIFETIME_SAFETY "Resource Lifetime Safety"
+#define EXECUTION_CONTEXT_SAFETY "Execution Context Safety"
+#define PROGRAM_STRUCTURE "Program Structure"
+#define POLICY "Policy"
+#define VERIFIER_LIMIT "Verifier Limit"
+
+bool bpf_diag_enabled(const struct bpf_verifier_env *env)
+{
+ return env->log.level & BPF_LOG_LEVEL;
+}
+
+static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+
+static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...)
+{
+ va_list args;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ va_start(args, fmt);
+ bpf_verifier_vlog(&env->log, fmt, args);
+ va_end(args);
+}
+
+void bpf_diag_header(struct bpf_verifier_env *env, const char *category, const char *problem)
+{
+ char first;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ category = category ?: "Verifier Error";
+ problem = problem ?: "";
+
+ if (!problem[0]) {
+ diag_write(env, "\nVerification failed: %s\n", category);
+ return;
+ }
+
+ first = toupper(problem[0]);
+ diag_write(env, "\nVerification failed: %s: %c%s\n", category, first, problem + 1);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
new file mode 100644
index 000000000000..e8e4c06233e2
--- /dev/null
+++ b/kernel/bpf/diagnostics.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
+
+#ifndef __BPF_DIAGNOSTICS_H
+#define __BPF_DIAGNOSTICS_H
+
+#include <linux/compiler_attributes.h>
+#include <linux/types.h>
+
+struct bpf_verifier_env;
+
+bool bpf_diag_enabled(const struct bpf_verifier_env *env);
+void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
+ const char *problem);
+
+#endif /* __BPF_DIAGNOSTICS_H */
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-13 0:15 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 03/16] bpf: Add verifier diagnostic event log Kumar Kartikeya Dwivedi
` (14 subsequent siblings)
16 siblings, 1 reply; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Teach verifier diagnostics to annotate an instruction with BTF source
line information and nearby BPF instructions. The renderer keeps source
text in a fixed-width lane and prints instructions in a stable right-hand
gutter.
Wrap annotation text under the source line so long error labels remain
readable while the source and instruction lanes keep their fixed layout.
Keeping source and instruction context in one commit preserves the visual
layout contract that later diagnostic reports rely on.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
include/linux/bpf.h | 13 +-
include/linux/bpf_verifier.h | 4 +
include/linux/btf.h | 1 +
kernel/bpf/btf.c | 10 +
kernel/bpf/core.c | 35 ++-
kernel/bpf/diagnostics.c | 511 +++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 8 +
kernel/bpf/verifier.c | 32 ++-
8 files changed, 581 insertions(+), 33 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b4a10c9878cf..7aad3bbed412 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -4147,8 +4147,17 @@ static inline bool bpf_is_subprog(const struct bpf_prog *prog)
}
const struct bpf_line_info *bpf_find_linfo(const struct bpf_prog *prog, u32 insn_off);
-void bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
- const char **filep, const char **linep, int *nump);
+#define BPF_LINFO_LINE_TRIM 1
+struct bpf_linfo_source {
+ const char *file;
+ const char *line;
+ u32 file_name_off;
+ int line_num;
+ int line_col;
+};
+
+void bpf_get_linfo_source(struct btf *btf, const struct bpf_line_info *linfo,
+ struct bpf_linfo_source *src, u32 flags);
int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,
const char **linep, int *nump);
struct bpf_prog *bpf_prog_find_from_stack(void);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 93f7c2075eea..14cc174d31c1 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -830,6 +830,7 @@ static inline u16 bpf_in_stack_arg_cnt(const struct bpf_subprog_info *sub)
return 0;
}
+struct bpf_diag;
struct bpf_verifier_env;
struct backtrack_state {
@@ -946,6 +947,7 @@ struct bpf_verifier_env {
struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
const struct bpf_line_info *prev_linfo;
struct bpf_verifier_log log;
+ struct bpf_diag *diag;
struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 2]; /* max + 2 for the fake and exception subprogs */
/* subprog indices sorted in topological order: leaves first, callers last */
int subprog_topo_order[BPF_MAX_SUBPROGS + 2];
@@ -1429,8 +1431,10 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_verifie
void print_insn_state(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate,
u32 frameno);
u32 bpf_vlog_alignment(u32 pos);
+const char *bpf_disasm_kfunc_name(void *data, const struct bpf_insn *insn);
struct bpf_subprog_info *bpf_find_containing_subprog(struct bpf_verifier_env *env, int off);
+const char *bpf_subprog_name(const struct bpf_verifier_env *env, int subprog);
int bpf_jmp_offset(struct bpf_insn *insn);
struct bpf_iarray *bpf_insn_successors(struct bpf_verifier_env *env, u32 idx);
void bpf_fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask);
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 3f5255d095a2..d81e42551365 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -214,6 +214,7 @@ int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
*/
int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
char *buf, int len, u64 flags);
+int btf_type_snprintf_show_name(const struct btf *btf, u32 type_id, char *buf, int len);
int btf_get_fd_by_id(u32 id);
u32 btf_obj_id(const struct btf *btf);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6606187ed4f4..5a6bab348aa1 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8317,6 +8317,16 @@ int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
return ssnprintf.len;
}
+int btf_type_snprintf_show_name(const struct btf *btf, u32 type_id, char *buf, int len)
+{
+ struct btf_show show = {
+ .btf = btf,
+ .state.type_id = type_id,
+ };
+
+ return snprintf(buf, len, "%s", btf_show_name(&show));
+}
+
#ifdef CONFIG_PROC_FS
static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
{
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index a3e1fae32eac..92b6b9d1f770 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -3477,24 +3477,16 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(xdp_bulk_tx);
#ifdef CONFIG_BPF_SYSCALL
-void bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
- const char **filep, const char **linep, int *nump)
+void bpf_get_linfo_source(struct btf *btf, const struct bpf_line_info *linfo,
+ struct bpf_linfo_source *src, u32 flags)
{
- /* Get base component of the file path. */
- if (filep) {
- *filep = btf_name_by_offset(btf, linfo->file_name_off);
- *filep = kbasename(*filep);
- }
-
- /* Obtain the source line, and strip whitespace in prefix. */
- if (linep) {
- *linep = btf_name_by_offset(btf, linfo->line_off);
- while (isspace(**linep))
- *linep += 1;
- }
-
- if (nump)
- *nump = BPF_LINE_INFO_LINE_NUM(linfo->line_col);
+ src->file = kbasename(btf_name_by_offset(btf, linfo->file_name_off));
+ src->line = btf_name_by_offset(btf, linfo->line_off);
+ while ((flags & BPF_LINFO_LINE_TRIM) && isspace(*src->line))
+ src->line++;
+ src->file_name_off = linfo->file_name_off;
+ src->line_num = BPF_LINE_INFO_LINE_NUM(linfo->line_col);
+ src->line_col = BPF_LINE_INFO_LINE_COL(linfo->line_col);
}
const struct bpf_line_info *bpf_find_linfo(const struct bpf_prog *prog, u32 insn_off)
@@ -3537,6 +3529,7 @@ const struct bpf_line_info *bpf_find_linfo(const struct bpf_prog *prog, u32 insn
int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,
const char **linep, int *nump)
{
+ struct bpf_linfo_source src;
int idx = -1, insn_start, insn_end, len;
struct bpf_line_info *linfo;
void **jited_linfo;
@@ -3568,7 +3561,13 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
if (idx == -1)
return -ENOENT;
- bpf_get_linfo_file_line(btf, &linfo[idx], filep, linep, nump);
+ bpf_get_linfo_source(btf, &linfo[idx], &src, BPF_LINFO_LINE_TRIM);
+ if (filep)
+ *filep = src.file;
+ if (linep)
+ *linep = src.line;
+ if (nump)
+ *nump = src.line_num;
return 0;
}
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index ba57aabd399f..77dcffb9adee 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1,10 +1,18 @@
// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2026 Meta Platforms, Inc. and affiliates.
+#include <linux/bpf.h>
#include <linux/bpf_verifier.h>
+#include <linux/btf.h>
#include <linux/ctype.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/seq_buf.h>
+#include <linux/slab.h>
#include <linux/stdarg.h>
+#include <linux/string.h>
+#include "disasm.h"
#include "diagnostics.h"
#define MEMORY_SAFETY "Memory Safety"
@@ -16,6 +24,50 @@
#define POLICY "Policy"
#define VERIFIER_LIMIT "Verifier Limit"
+#define BPF_DIAG_TEXT_WIDTH 100
+#define BPF_DIAG_MSG_LEN 512
+#define BPF_DIAG_CONTEXT 2
+#define BPF_DIAG_CONTEXT_CNT (1 + BPF_DIAG_CONTEXT * 2)
+#define BPF_DIAG_SOURCE_LANE_WIDTH 88
+#define BPF_DIAG_TAB_WIDTH 8
+#define BPF_DIAG_REG_DESC_LEN 512
+#define BPF_DIAG_REG_TMP_LEN 192
+#define BPF_DIAG_FMT_CHUNK_SIZE 1024
+#define BPF_DIAG_FMT_BUF_SIZE 256
+#define DISASM_LINE_LEN 160
+
+struct disasm_line {
+ char text[DISASM_LINE_LEN];
+ int idx;
+ bool valid;
+};
+
+struct disasm_ctx {
+ struct bpf_verifier_env *env;
+ struct seq_buf seq;
+};
+
+struct diag_fmt_chunk {
+ struct list_head node;
+ struct seq_buf seq;
+ char data[];
+};
+
+struct diag_fmt_mark {
+ struct diag_fmt_chunk *chunk;
+ size_t len;
+};
+
+struct bpf_diag_scratch {
+ struct bpf_linfo_source source_lines[BPF_DIAG_CONTEXT_CNT];
+ struct disasm_line disasm_lines[BPF_DIAG_CONTEXT_CNT];
+};
+
+struct bpf_diag {
+ struct bpf_diag_scratch scratch;
+ struct list_head fmt_chunks;
+};
+
bool bpf_diag_enabled(const struct bpf_verifier_env *env)
{
return env->log.level & BPF_LOG_LEVEL;
@@ -23,6 +75,164 @@ bool bpf_diag_enabled(const struct bpf_verifier_env *env)
static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+static struct bpf_diag *diag_env(struct bpf_verifier_env *env)
+{
+ return env->diag;
+}
+
+int bpf_diag_init(struct bpf_verifier_env *env)
+{
+ if (!bpf_diag_enabled(env))
+ return 0;
+
+ env->diag = kzalloc_obj(struct bpf_diag, GFP_KERNEL_ACCOUNT);
+ if (!env->diag)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&env->diag->fmt_chunks);
+ return 0;
+}
+
+static struct bpf_diag_scratch *diag_scratch(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+
+ return diag ? &diag->scratch : NULL;
+}
+
+static char *diag_fmt_alloc(struct bpf_verifier_env *env, size_t size)
+{
+ struct bpf_diag *diag = diag_env(env);
+ struct diag_fmt_chunk *chunk;
+ size_t capacity, available;
+ char *buf;
+
+ if (!diag || !size || size > INT_MAX)
+ return NULL;
+
+ if (!list_empty(&diag->fmt_chunks)) {
+ chunk = list_last_entry(&diag->fmt_chunks, struct diag_fmt_chunk, node);
+ available = seq_buf_get_buf(&chunk->seq, &buf);
+ if (available >= size)
+ goto commit;
+ }
+
+ capacity = max_t(size_t, BPF_DIAG_FMT_CHUNK_SIZE, size);
+ chunk = kmalloc(struct_size(chunk, data, capacity), GFP_KERNEL_ACCOUNT);
+ if (!chunk)
+ return NULL;
+
+ seq_buf_init(&chunk->seq, chunk->data, capacity);
+ list_add_tail(&chunk->node, &diag->fmt_chunks);
+ available = seq_buf_get_buf(&chunk->seq, &buf);
+ if (WARN_ON_ONCE(available < size))
+ return NULL;
+
+commit:
+ seq_buf_commit(&chunk->seq, size);
+ return buf;
+}
+
+char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size)
+{
+ char *buf;
+
+ buf = diag_fmt_alloc(env, size);
+ if (buf)
+ buf[0] = '\0';
+ return buf;
+}
+
+const char *bpf_diag_vfmt(struct bpf_verifier_env *env, const char *fmt, va_list args)
+{
+ va_list copy;
+ char *buf;
+ int len;
+
+ va_copy(copy, args);
+ len = vsnprintf(NULL, 0, fmt, copy);
+ va_end(copy);
+ if (len < 0 || len == INT_MAX)
+ return "";
+
+ buf = diag_fmt_alloc(env, len + 1);
+ if (buf)
+ vsnprintf(buf, len + 1, fmt, args);
+ return buf ?: "";
+}
+
+const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...)
+{
+ const char *buf;
+ va_list args;
+
+ va_start(args, fmt);
+ buf = bpf_diag_vfmt(env, fmt, args);
+ va_end(args);
+ return buf;
+}
+
+static struct diag_fmt_mark diag_fmt_save(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+ struct diag_fmt_mark mark = {};
+
+ if (!diag || list_empty(&diag->fmt_chunks))
+ return mark;
+
+ mark.chunk = list_last_entry(&diag->fmt_chunks, struct diag_fmt_chunk, node);
+ mark.len = mark.chunk->seq.len;
+ return mark;
+}
+
+static void diag_fmt_restore(struct bpf_verifier_env *env, struct diag_fmt_mark mark)
+{
+ struct bpf_diag *diag = diag_env(env);
+ struct diag_fmt_chunk *chunk;
+
+ if (!diag)
+ return;
+
+ while (!list_empty(&diag->fmt_chunks)) {
+ chunk = list_last_entry(&diag->fmt_chunks, struct diag_fmt_chunk, node);
+ if (chunk == mark.chunk)
+ break;
+ list_del(&chunk->node);
+ kfree(chunk);
+ }
+
+ if (mark.chunk) {
+ mark.chunk->seq.len = mark.len;
+ seq_buf_str(&mark.chunk->seq);
+ }
+}
+
+static void diag_fmt_free(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+ struct diag_fmt_chunk *chunk, *tmp;
+
+ if (!diag)
+ return;
+
+ list_for_each_entry_safe(chunk, tmp, &diag->fmt_chunks, node) {
+ list_del(&chunk->node);
+ kfree(chunk);
+ }
+}
+
+void bpf_diag_free(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = env->diag;
+
+ if (!diag)
+ return;
+
+ diag_fmt_free(env);
+ kfree(diag);
+ env->diag = NULL;
+}
+
static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...)
{
va_list args;
@@ -35,6 +245,182 @@ static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args);
}
+static void diag_print_wrapped_prefixed(struct bpf_verifier_env *env, const char *first_prefix,
+ const char *next_prefix, const char *text)
+{
+ const char *prefix = first_prefix;
+
+ while (*text) {
+ const char *line = text;
+ int prefix_len = strlen(prefix);
+ int text_width = BPF_DIAG_TEXT_WIDTH - prefix_len;
+ int len = 0, last_space = -1;
+
+ if (text_width < 1)
+ text_width = 1;
+
+ while (line[len] && line[len] != '\n' && len < text_width) {
+ if (line[len] == ' ')
+ last_space = len;
+ len++;
+ }
+
+ if (line[len] && line[len] != '\n' && line[len] != ' ' && last_space > 0)
+ len = last_space;
+
+ diag_write(env, "%s%.*s\n", prefix, len, line);
+
+ text = line + len;
+ while (*text == ' ')
+ text++;
+ if (*text == '\n')
+ text++;
+
+ prefix = next_prefix;
+ }
+}
+
+static int diag_line_width(unsigned int line)
+{
+ int width = 1;
+
+ while (line >= 10) {
+ line /= 10;
+ width++;
+ }
+
+ return width;
+}
+
+static int diag_line_indent(const char *line)
+{
+ int indent = 0;
+
+ while (*line == ' ' || *line == '\t') {
+ if (*line == '\t')
+ indent = round_up(indent + 1, BPF_DIAG_TAB_WIDTH);
+ else
+ indent++;
+ line++;
+ }
+
+ return indent;
+}
+
+static void disasm_print(void *private_data, const char *fmt, ...) __printf(2, 3);
+
+static void disasm_print(void *private_data, const char *fmt, ...)
+{
+ struct disasm_ctx *ctx = private_data;
+ va_list args;
+
+ va_start(args, fmt);
+ seq_buf_vprintf(&ctx->seq, fmt, args);
+ va_end(args);
+}
+
+static const char *disasm_kfunc_name(void *private_data, const struct bpf_insn *insn)
+{
+ struct disasm_ctx *ctx = private_data;
+
+ return bpf_disasm_kfunc_name(ctx->env, insn);
+}
+
+static void format_disasm_line(struct bpf_verifier_env *env, int insn_idx,
+ struct disasm_line *line)
+{
+ struct disasm_ctx ctx = { .env = env };
+ struct bpf_insn *insn;
+ const struct bpf_insn_cbs cbs = {
+ .cb_call = disasm_kfunc_name,
+ .cb_print = disasm_print,
+ .private_data = &ctx,
+ };
+
+ line->idx = insn_idx;
+ line->valid = false;
+ seq_buf_init(&ctx.seq, line->text, sizeof(line->text));
+
+ if (insn_idx < 0 || insn_idx >= env->prog->len)
+ return;
+
+ if (insn_idx > 0 && bpf_is_ldimm64(&env->prog->insnsi[insn_idx - 1]))
+ return;
+
+ insn = &env->prog->insnsi[insn_idx];
+ if (bpf_is_ldimm64(insn) && insn_idx + 1 >= env->prog->len)
+ return;
+
+ print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+ seq_buf_str(&ctx.seq);
+ ctx.seq.len = strnlen(line->text, sizeof(line->text));
+ while (ctx.seq.len && line->text[ctx.seq.len - 1] == '\n')
+ seq_buf_pop(&ctx.seq);
+ seq_buf_str(&ctx.seq);
+
+ line->valid = true;
+}
+
+static void diag_format_source_text(char *buf, size_t size, const char *line, int width)
+{
+ int col = 0, len = 0;
+
+ if (!size)
+ return;
+ if (width <= 0) {
+ buf[0] = '\0';
+ return;
+ }
+
+ line = line ?: "...";
+ while (*line && col < width && len + 1 < size) {
+ if (*line == '\t') {
+ int next = round_up(col + 1, BPF_DIAG_TAB_WIDTH);
+
+ while (col < next && col < width && len + 1 < size) {
+ buf[len++] = ' ';
+ col++;
+ }
+ line++;
+ continue;
+ }
+
+ buf[len++] = *line++;
+ col++;
+ }
+
+ if (*line) {
+ int ellipsis_len = min(3, width);
+
+ while (len > 0 && col > width - ellipsis_len) {
+ len--;
+ col--;
+ }
+ while (ellipsis_len-- && len + 1 < size)
+ buf[len++] = '.';
+ }
+
+ buf[len] = '\0';
+}
+
+static void diag_format_source_lane(char *buf, size_t size, const char *source_prefix,
+ int source_line_width, int line_num, const char *line)
+{
+ int len, text_width;
+
+ if (line_num <= 0) {
+ buf[0] = '\0';
+ return;
+ }
+
+ len = scnprintf(buf, size, "%s%*d | ", source_prefix, source_line_width, line_num);
+ if (len >= (int)size)
+ return;
+
+ text_width = BPF_DIAG_SOURCE_LANE_WIDTH - len;
+ diag_format_source_text(buf + len, size - len, line, text_width);
+}
+
void bpf_diag_header(struct bpf_verifier_env *env, const char *category, const char *problem)
{
char first;
@@ -53,3 +439,128 @@ void bpf_diag_header(struct bpf_verifier_env *env, const char *category, const c
first = toupper(problem[0]);
diag_write(env, "\nVerification failed: %s: %c%s\n", category, first, problem + 1);
}
+
+static void diag_print_source_annotation(struct bpf_verifier_env *env, int line_width, int indent,
+ const char *label, const char *msg)
+{
+ const char *first_prefix, *next_prefix, *text;
+
+ indent = min_t(int, indent, max_t(int, 0, BPF_DIAG_SOURCE_LANE_WIDTH - line_width - 8));
+ text = bpf_diag_fmt(env, "%s: %s", label, msg);
+ first_prefix = bpf_diag_fmt(env, " %*s | %*s^-- ", line_width + 4, "", indent, "");
+ next_prefix = bpf_diag_fmt(env, " %*s | %*s ", line_width + 4, "", indent, "");
+
+ diag_print_wrapped_prefixed(env, first_prefix, next_prefix, text);
+}
+
+void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
+ const char *fmt, ...)
+{
+ struct bpf_diag_scratch *scratch;
+ struct bpf_linfo_source *source_lines;
+ struct disasm_line *disasm_lines;
+ struct bpf_linfo_source src;
+ struct diag_fmt_mark mark;
+ const struct bpf_line_info *linfo;
+ const struct bpf_subprog_info *subprog;
+ struct btf *btf = env->prog->aux->btf;
+ char *source_lane;
+ const char *msg;
+ const char *func;
+ int start_line, end_line, width, indent, insn_width, subprogno, i;
+ va_list args;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ mark = diag_fmt_save(env);
+ label = label ?: "note";
+ scratch = diag_scratch(env);
+ source_lines = scratch->source_lines;
+ disasm_lines = scratch->disasm_lines;
+ memset(source_lines, 0, sizeof(scratch->source_lines));
+ memset(disasm_lines, 0, sizeof(scratch->disasm_lines));
+
+ va_start(args, fmt);
+ msg = bpf_diag_vfmt(env, fmt, args);
+ va_end(args);
+ if (!*msg)
+ msg = "<failed to allocate diagnostic text>";
+
+ linfo = bpf_find_linfo(env->prog, insn_idx);
+ if (!btf || !linfo) {
+ diag_write(env, " insn %u\n", insn_idx);
+ diag_print_source_annotation(env, 0, 0, label, msg);
+ goto out_restore;
+ }
+ bpf_get_linfo_source(btf, linfo, &src, 0);
+ if (!src.file || !*src.file || !src.line || !*src.line) {
+ diag_write(env, " insn %u\n", insn_idx);
+ diag_print_source_annotation(env, 0, 0, label, msg);
+ goto out_restore;
+ }
+
+ subprog = bpf_find_containing_subprog(env, insn_idx);
+ subprogno = subprog ? bpf_find_subprog(env, subprog->start) : -ENOENT;
+ func = subprogno >= 0 ? bpf_subprog_name(env, subprogno) : NULL;
+ if (func && *func)
+ diag_write(env, " %s @ %s:%d:%d\n", func, src.file, src.line_num, src.line_col);
+ else
+ diag_write(env, " %s:%d:%d\n", src.file, src.line_num, src.line_col);
+
+ start_line = src.line_num - BPF_DIAG_CONTEXT;
+ end_line = src.line_num + BPF_DIAG_CONTEXT;
+ width = diag_line_width(end_line);
+ indent = diag_line_indent(src.line);
+ insn_width = diag_line_width(env->prog->len ? env->prog->len - 1 : 0);
+ for (i = 0; i < BPF_DIAG_CONTEXT_CNT; i++)
+ source_lines[i].line_num = start_line + i;
+
+ linfo = env->prog->aux->linfo;
+ for (i = 0; i < env->prog->aux->nr_linfo; i++) {
+ struct bpf_linfo_source line_src;
+ int idx;
+
+ bpf_get_linfo_source(btf, &linfo[i], &line_src, 0);
+ if (line_src.file_name_off != src.file_name_off ||
+ line_src.line_num < start_line || line_src.line_num > end_line ||
+ !line_src.line || !*line_src.line)
+ continue;
+
+ idx = line_src.line_num - start_line;
+ if (!source_lines[idx].line)
+ source_lines[idx] = line_src;
+ }
+
+ for (i = 0; i < BPF_DIAG_CONTEXT_CNT; i++) {
+ int row = i - BPF_DIAG_CONTEXT;
+
+ format_disasm_line(env, insn_idx + row, &disasm_lines[i]);
+ }
+
+ diag_write(env, " Source context:\n");
+ source_lane = bpf_diag_fmt_buf(env, BPF_DIAG_FMT_BUF_SIZE);
+ if (!source_lane)
+ goto out_restore;
+ for (i = 0; i < BPF_DIAG_CONTEXT_CNT; i++) {
+ const char *source_prefix;
+
+ source_prefix = source_lines[i].line_num == src.line_num ? ">>> " : " ";
+ diag_format_source_lane(source_lane, BPF_DIAG_FMT_BUF_SIZE, source_prefix, width,
+ source_lines[i].line_num, source_lines[i].line);
+ diag_write(env, " %s\n", source_lane);
+ if (source_lines[i].line_num == src.line_num)
+ diag_print_source_annotation(env, width, indent, label, msg);
+ }
+ diag_write(env, " Instruction context:\n");
+ for (i = 0; i < BPF_DIAG_CONTEXT_CNT; i++) {
+ struct disasm_line *line = &disasm_lines[i];
+
+ if (line->valid)
+ diag_write(env, " %s%*d | %s\n", line->idx == insn_idx ? ">>> " : " ",
+ insn_width, line->idx, line->text);
+ }
+
+out_restore:
+ diag_fmt_restore(env, mark);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index e8e4c06233e2..7b391cf49ae5 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -10,7 +10,15 @@
struct bpf_verifier_env;
bool bpf_diag_enabled(const struct bpf_verifier_env *env);
+int bpf_diag_init(struct bpf_verifier_env *env);
+char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size);
+const char *bpf_diag_vfmt(struct bpf_verifier_env *env, const char *fmt, va_list args)
+ __printf(2, 0);
+const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+void bpf_diag_free(struct bpf_verifier_env *env);
void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
const char *problem);
+void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
+ const char *fmt, ...) __printf(4, 5);
#endif /* __BPF_DIAGNOSTICS_H */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 61ef43325c6f..6bc2ccf35971 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -34,6 +34,7 @@
#include <linux/trace_events.h>
#include <linux/kallsyms.h>
+#include "diagnostics.h"
#include "disasm.h"
static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
@@ -405,7 +406,7 @@ static bool subprog_returns_void(struct bpf_verifier_env *env, int subprog)
return btf_type_is_void(type);
}
-static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
+const char *bpf_subprog_name(const struct bpf_verifier_env *env, int subprog)
{
struct bpf_func_info *info;
@@ -3032,8 +3033,8 @@ static int sort_subprogs_topo(struct bpf_verifier_env *env)
if (bpf_pseudo_func(&insn[idx]))
continue;
verbose(env, "recursive call from %s() to %s()\n",
- subprog_name(env, cur),
- subprog_name(env, callee));
+ bpf_subprog_name(env, cur),
+ bpf_subprog_name(env, callee));
ret = -EINVAL;
goto out;
}
@@ -3053,8 +3054,8 @@ static int sort_subprogs_topo(struct bpf_verifier_env *env)
if (env->log.level & BPF_LOG_LEVEL2)
for (i = 0; i < cnt; i++)
- verbose(env, "topo_order[%d] = %s\n",
- i, subprog_name(env, env->subprog_topo_order[i]));
+ verbose(env, "topo_order[%d] = %s\n", i,
+ bpf_subprog_name(env, env->subprog_topo_order[i]));
out:
kvfree(dfs_stack);
kvfree(color);
@@ -3198,7 +3199,7 @@ static void linked_regs_unpack(u64 val, struct linked_regs *s)
}
}
-static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
+const char *bpf_disasm_kfunc_name(void *data, const struct bpf_insn *insn)
{
const struct btf_type *func;
struct btf *desc_btf;
@@ -3217,9 +3218,9 @@ static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
void bpf_verbose_insn(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
const struct bpf_insn_cbs cbs = {
- .cb_call = disasm_kfunc_name,
- .cb_print = verbose,
- .private_data = env,
+ .cb_call = bpf_disasm_kfunc_name,
+ .cb_print = verbose,
+ .private_data = env,
};
print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
@@ -9391,7 +9392,7 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (err == -EFAULT)
return err;
if (bpf_subprog_is_global(env, subprog)) {
- const char *sub_name = subprog_name(env, subprog);
+ const char *sub_name = bpf_subprog_name(env, subprog);
if (env->cur_state->active_locks) {
verbose(env, "global function calls are not allowed while holding a lock,\n"
@@ -18433,7 +18434,7 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
regs = state->frame[state->curframe]->regs;
if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
- const char *sub_name = subprog_name(env, subprog);
+ const char *sub_name = bpf_subprog_name(env, subprog);
struct bpf_subprog_arg_info *arg;
struct bpf_reg_state *reg;
@@ -18603,8 +18604,9 @@ static int do_check_subprogs(struct bpf_verifier_env *env)
if (ret) {
return ret;
} else if (env->log.level & BPF_LOG_LEVEL) {
- verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n",
- i, subprog_name(env, i));
+ verbose(env,
+ "Func#%d ('%s') is safe for any args that match its prototype\n", i,
+ bpf_subprog_name(env, i));
}
/* We verified new global subprog, it might have called some
@@ -20134,6 +20136,9 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr,
ret = bpf_vlog_init(&env->log, attr_log->level, attr_log->ubuf, attr_log->size);
if (ret)
goto err_free_env;
+ ret = bpf_diag_init(env);
+ if (ret)
+ goto err_prep;
if (env->signature) {
ret = bpf_prog_calc_tag(env->prog);
if (ret < 0)
@@ -20424,6 +20429,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr,
kvfree(env->scc_info);
kvfree(env->succ);
kvfree(env->gotox_tmp_buf);
+ bpf_diag_free(env);
kvfree(env);
return ret;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 03/16] bpf: Add verifier diagnostic event log
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 04/16] bpf: Prune verifier diagnostics when switching paths Kumar Kartikeya Dwivedi
` (13 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Add an environment-owned diagnostic history for verifier reports. Event
payloads keep the user-facing branch history shape, while storage lives
in bpf_verifier_env and follows the active verifier path.
Grow the event array as entries are appended and keep saved positions as
array indices. Later patches can truncate back to those positions when
verifier search backtracks. Add the branch event renderer and branch
recording.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 108 +++++++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 3 ++
kernel/bpf/verifier.c | 21 ++++++++
3 files changed, 132 insertions(+)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 77dcffb9adee..0e0aa3a7106c 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -34,8 +34,24 @@
#define BPF_DIAG_REG_TMP_LEN 192
#define BPF_DIAG_FMT_CHUNK_SIZE 1024
#define BPF_DIAG_FMT_BUF_SIZE 256
+#define BPF_DIAG_EVENT_LOG_MAX_SIZE (1U << 20)
#define DISASM_LINE_LEN 160
+enum bpf_diag_history_kind {
+ BPF_DIAG_HISTORY_BRANCH,
+};
+
+struct bpf_diag_history_event {
+ u32 insn_idx : 24;
+ u32 kind : 8;
+ u8 in_lineage : 1;
+ union {
+ struct {
+ bool cond_true;
+ } branch;
+ };
+};
+
struct disasm_line {
char text[DISASM_LINE_LEN];
int idx;
@@ -58,12 +74,21 @@ struct diag_fmt_mark {
size_t len;
};
+struct bpf_diag_log {
+ struct bpf_diag_history_event *events;
+ u32 cnt;
+ u32 cap;
+ u32 dropped;
+ bool capped;
+};
+
struct bpf_diag_scratch {
struct bpf_linfo_source source_lines[BPF_DIAG_CONTEXT_CNT];
struct disasm_line disasm_lines[BPF_DIAG_CONTEXT_CNT];
};
struct bpf_diag {
+ struct bpf_diag_log log;
struct bpf_diag_scratch scratch;
struct list_head fmt_chunks;
};
@@ -229,6 +254,7 @@ void bpf_diag_free(struct bpf_verifier_env *env)
return;
diag_fmt_free(env);
+ kvfree(diag->log.events);
kfree(diag);
env->diag = NULL;
}
@@ -245,6 +271,75 @@ static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args);
}
+static struct bpf_diag_log *diag_event_log(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+
+ return diag ? &diag->log : NULL;
+}
+
+u32 bpf_diag_event_log_pos(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+
+ if (!diag)
+ return 0;
+ return diag->log.cnt;
+}
+
+void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos)
+{
+ struct bpf_diag *diag = env->diag;
+ struct bpf_diag_log *log;
+ u32 end;
+
+ if (!diag)
+ return;
+
+ log = &diag->log;
+ end = log->cnt;
+ if (WARN_ON_ONCE(pos > end))
+ pos = end;
+
+ log->cnt = pos;
+}
+
+static void diag_append_history(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_event *event)
+{
+ struct bpf_diag_history_event *events;
+ struct bpf_diag_log *log;
+ u32 cap, max_events;
+
+ log = diag_event_log(env);
+ if (!log)
+ return;
+
+ if (log->cnt < log->cap) {
+ log->events[log->cnt++] = *event;
+ return;
+ }
+
+ max_events = BPF_DIAG_EVENT_LOG_MAX_SIZE / sizeof(*events);
+ if (log->capped || log->cap == max_events) {
+ if (log->dropped != U32_MAX)
+ log->dropped++;
+ return;
+ }
+
+ cap = min_t(u32, log->cap ? log->cap * 2 : 64, max_events);
+ events = kvrealloc(log->events, array_size(cap, sizeof(*events)), GFP_KERNEL_ACCOUNT);
+ if (!events) {
+ log->capped = true;
+ if (log->dropped != U32_MAX)
+ log->dropped++;
+ return;
+ }
+ log->events = events;
+ log->cap = cap;
+ log->events[log->cnt++] = *event;
+}
+
static void diag_print_wrapped_prefixed(struct bpf_verifier_env *env, const char *first_prefix,
const char *next_prefix, const char *text)
{
@@ -564,3 +659,16 @@ void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *lab
out_restore:
diag_fmt_restore(env, mark);
}
+
+void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true)
+{
+ struct bpf_diag_history_event event = {
+ .insn_idx = insn_idx,
+ .kind = BPF_DIAG_HISTORY_BRANCH,
+ .branch = {
+ .cond_true = cond_true,
+ },
+ };
+
+ diag_append_history(env, &event);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 7b391cf49ae5..9cc6b4747a06 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -15,10 +15,13 @@ char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size);
const char *bpf_diag_vfmt(struct bpf_verifier_env *env, const char *fmt, va_list args)
__printf(2, 0);
const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+u32 bpf_diag_event_log_pos(struct bpf_verifier_env *env);
+void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos);
void bpf_diag_free(struct bpf_verifier_env *env);
void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
const char *problem);
void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
const char *fmt, ...) __printf(4, 5);
+void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
#endif /* __BPF_DIAGNOSTICS_H */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6bc2ccf35971..6ca366ff5037 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -17369,6 +17369,27 @@ static int do_check(struct bpf_verifier_env *env)
state->last_insn_idx = env->prev_insn_idx;
state->insn_idx = env->insn_idx;
+ /*
+ * Record the incoming edge so active and queued paths use the same
+ * branch-recording path. A zero-offset conditional has identical
+ * successors, so its outcome cannot be reconstructed from the edge.
+ */
+ if (!state->speculative && prev_insn_idx >= 0 && prev_insn_idx < insn_cnt) {
+ struct bpf_insn *prev_insn = &insns[prev_insn_idx];
+ int fallthrough_idx = prev_insn_idx + 1;
+ int branch_idx = prev_insn_idx + bpf_jmp_offset(prev_insn) + 1;
+ u8 class = BPF_CLASS(prev_insn->code);
+ u8 opcode = BPF_OP(prev_insn->code);
+
+ if ((class == BPF_JMP || class == BPF_JMP32) &&
+ opcode != BPF_JA && opcode != BPF_CALL && opcode != BPF_EXIT &&
+ opcode <= BPF_JCOND && branch_idx != fallthrough_idx) {
+ if (env->insn_idx == branch_idx)
+ bpf_diag_record_branch(env, prev_insn_idx, true);
+ else if (env->insn_idx == fallthrough_idx)
+ bpf_diag_record_branch(env, prev_insn_idx, false);
+ }
+ }
if (bpf_is_prune_point(env, env->insn_idx)) {
err = bpf_is_state_visited(env, env->insn_idx);
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 04/16] bpf: Prune verifier diagnostics when switching paths
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (2 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 03/16] bpf: Add verifier diagnostic event log Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events Kumar Kartikeya Dwivedi
` (12 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Save the diagnostic event-log position with each verifier stack entry and
reset the environment-owned stream together with the normal verifier log
when a queued state is popped. Also reset the diagnostic stream after
successful subprogram verification even when level-2 logging preserves the
normal verifier log.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/verifier.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6ca366ff5037..2e915292265b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -194,6 +194,7 @@ struct bpf_verifier_stack_elem {
struct bpf_verifier_stack_elem *next;
/* length of verifier log at the time this state was pushed on stack */
u32 log_pos;
+ u32 diag_log_pos;
};
#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
@@ -1700,6 +1701,7 @@ static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
err = bpf_copy_verifier_state(cur, &head->st);
if (err)
return err;
+ bpf_diag_event_log_reset(env, head->diag_log_pos);
}
if (pop_log)
bpf_vlog_reset(&env->log, head->log_pos);
@@ -1743,6 +1745,7 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
elem->prev_insn_idx = prev_insn_idx;
elem->next = env->head;
elem->log_pos = env->log.end_pos;
+ elem->diag_log_pos = bpf_diag_event_log_pos(env);
env->head = elem;
env->stack_size++;
err = bpf_copy_verifier_state(&elem->st, cur);
@@ -2264,6 +2267,7 @@ static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
elem->prev_insn_idx = prev_insn_idx;
elem->next = env->head;
elem->log_pos = env->log.end_pos;
+ elem->diag_log_pos = bpf_diag_event_log_pos(env);
env->head = elem;
env->stack_size++;
if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
@@ -18566,8 +18570,11 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
ret = do_check(env);
out:
- if (!ret && pop_log)
- bpf_vlog_reset(&env->log, 0);
+ if (!ret) {
+ if (pop_log)
+ bpf_vlog_reset(&env->log, 0);
+ bpf_diag_event_log_reset(env, 0);
+ }
free_states(env);
return ret;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (3 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 04/16] bpf: Prune verifier diagnostics when switching paths Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:53 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 06/16] bpf: Track verifier reference " Kumar Kartikeya Dwivedi
` (11 subsequent siblings)
16 siblings, 1 reply; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Record material register and outgoing stack argument changes so diagnostics can
explain how a value reached its current type, bounds, or unreadable state.
Store old and new register types, scalar ranges, tnum value and mask, map and
BTF type identity, and basic operand metadata in the environment-owned
diagnostic event stream.
Record invalidations when packet data moves, references are released, or
borrowed references leave their protected region. Register-scoped history
starts at the latest matching modification and then shows later branch
outcomes.
Also record fixed stack spills and overwrites, and tag register fills from
stack so register-scoped history can follow value flow through spilled stack
slots.
The type_is_map_ptr() helper previously lived as a static function in
kernel/bpf/log.c since commit 0c95c9fdb696 ("bpf: emit map name in register
state if applicable and available"). Move it verbatim to
include/linux/bpf_verifier.h as a static inline, next to the other type
classifiers, so diagnostics.c can reuse it without duplicating the case list.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
include/linux/bpf_verifier.h | 12 ++
kernel/bpf/diagnostics.c | 271 ++++++++++++++++++++++++++++++++++-
kernel/bpf/diagnostics.h | 80 +++++++++++
kernel/bpf/log.c | 11 --
kernel/bpf/verifier.c | 134 +++++++++++++----
5 files changed, 468 insertions(+), 40 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 14cc174d31c1..3786961c4efc 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -1347,6 +1347,18 @@ static inline bool type_is_non_owning_ref(u32 type)
return type_is_ptr_alloc_obj(type) && type_flag(type) & NON_OWN_REF;
}
+static inline bool type_is_map_ptr(enum bpf_reg_type type)
+{
+ switch (base_type(type)) {
+ case CONST_PTR_TO_MAP:
+ case PTR_TO_MAP_KEY:
+ case PTR_TO_MAP_VALUE:
+ return true;
+ default:
+ return false;
+ }
+}
+
static inline bool type_is_pkt_pointer(enum bpf_reg_type type)
{
type = base_type(type);
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 0e0aa3a7106c..460bb83ae33d 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -30,15 +30,23 @@
#define BPF_DIAG_CONTEXT_CNT (1 + BPF_DIAG_CONTEXT * 2)
#define BPF_DIAG_SOURCE_LANE_WIDTH 88
#define BPF_DIAG_TAB_WIDTH 8
-#define BPF_DIAG_REG_DESC_LEN 512
-#define BPF_DIAG_REG_TMP_LEN 192
#define BPF_DIAG_FMT_CHUNK_SIZE 1024
#define BPF_DIAG_FMT_BUF_SIZE 256
#define BPF_DIAG_EVENT_LOG_MAX_SIZE (1U << 20)
#define DISASM_LINE_LEN 160
+struct bpf_diag_reg_snapshot {
+ u32 type;
+ u32 btf_id;
+ const struct bpf_map *map_ptr;
+ const struct btf *btf;
+ struct tnum var_off;
+ struct cnum64 r64;
+};
+
enum bpf_diag_history_kind {
BPF_DIAG_HISTORY_BRANCH,
+ BPF_DIAG_HISTORY_MOD,
};
struct bpf_diag_history_event {
@@ -49,6 +57,13 @@ struct bpf_diag_history_event {
struct {
bool cond_true;
} branch;
+ struct {
+ struct bpf_diag_mod_target target;
+ struct bpf_diag_mod_target origin;
+ struct bpf_diag_reg_snapshot old, new;
+ u8 reason;
+ bool origin_valid;
+ } mod;
};
};
@@ -87,10 +102,21 @@ struct bpf_diag_scratch {
struct disasm_line disasm_lines[BPF_DIAG_CONTEXT_CNT];
};
+struct bpf_diag_mod_scope {
+ struct bpf_reg_state target_reg_snapshot;
+ struct bpf_diag_mod_target target;
+ struct bpf_diag_mod_target origin;
+ enum bpf_diag_mod_reason reason;
+ u32 insn_idx;
+ bool active;
+ bool origin_valid;
+};
+
struct bpf_diag {
struct bpf_diag_log log;
struct bpf_diag_scratch scratch;
struct list_head fmt_chunks;
+ struct bpf_diag_mod_scope mod;
};
bool bpf_diag_enabled(const struct bpf_verifier_env *env)
@@ -375,6 +401,34 @@ static void diag_print_wrapped_prefixed(struct bpf_verifier_env *env, const char
}
}
+static void bpf_diag_format_btf_type(char *buf, size_t size, const struct btf *btf, u32 type_id)
+{
+ size_t len;
+ int ret;
+
+ buf[0] = '\0';
+ ret = btf_type_snprintf_show_name(btf, type_id, buf, size);
+ if (ret < 0 || !buf[0]) {
+ scnprintf(buf, size, "BTF type ID %u", type_id);
+ return;
+ }
+
+ len = strlen(buf);
+ if (len && buf[len - 1] == '{')
+ buf[len - 1] = '\0';
+}
+
+const char *bpf_diag_fmt_btf_type(struct bpf_verifier_env *env, const struct btf *btf, u32 type_id)
+{
+ char *buf = bpf_diag_fmt_buf(env, BPF_DIAG_FMT_BUF_SIZE);
+
+ if (!buf)
+ return "";
+
+ bpf_diag_format_btf_type(buf, BPF_DIAG_FMT_BUF_SIZE, btf, type_id);
+ return buf;
+}
+
static int diag_line_width(unsigned int line)
{
int width = 1;
@@ -672,3 +726,216 @@ void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool con
diag_append_history(env, &event);
}
+
+static void diag_snapshot_reg(struct bpf_diag_reg_snapshot *snapshot,
+ const struct bpf_reg_state *reg)
+{
+ snapshot->type = reg->type;
+ if (type_is_map_ptr(reg->type))
+ snapshot->map_ptr = reg->map_ptr;
+ if (base_type(reg->type) == PTR_TO_BTF_ID && reg->btf && reg->btf_id) {
+ snapshot->btf_id = reg->btf_id;
+ snapshot->btf = reg->btf;
+ }
+ snapshot->var_off = reg->var_off;
+ snapshot->r64 = reg->r64;
+}
+
+static bool diag_snapshot_eq(const struct bpf_diag_reg_snapshot *old,
+ const struct bpf_diag_reg_snapshot *new)
+{
+ return old->type == new->type && old->map_ptr == new->map_ptr && old->btf == new->btf &&
+ old->btf_id == new->btf_id && old->var_off.value == new->var_off.value &&
+ old->var_off.mask == new->var_off.mask && old->r64.base == new->r64.base &&
+ old->r64.size == new->r64.size;
+}
+
+static bool diag_mod_insn_origin(struct bpf_verifier_env *env, u32 insn_idx,
+ const struct bpf_diag_mod_target *target,
+ struct bpf_diag_mod_target *origin)
+{
+ const struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
+ u8 class = BPF_CLASS(insn->code);
+ u32 frameno;
+
+ if (target->kind == BPF_DIAG_MOD_TARGET_REG && (class == BPF_ALU || class == BPF_ALU64) &&
+ BPF_OP(insn->code) == BPF_MOV && BPF_SRC(insn->code) == BPF_X) {
+ *origin = bpf_diag_reg_target(target->frameno, insn->src_reg);
+ return true;
+ }
+
+ if ((target->kind != BPF_DIAG_MOD_TARGET_STACK_ARG &&
+ target->kind != BPF_DIAG_MOD_TARGET_STACK_SLOT) ||
+ class != BPF_STX)
+ return false;
+
+ frameno = env->cur_state->frame[env->cur_state->curframe]->frameno;
+ *origin = bpf_diag_reg_target(frameno, insn->src_reg);
+ return true;
+}
+
+static void bpf_diag_record_mod(struct bpf_verifier_env *env, u32 insn_idx,
+ struct bpf_diag_mod_target target,
+ enum bpf_diag_mod_reason reason,
+ const struct bpf_reg_state *old_reg,
+ const struct bpf_reg_state *new_reg,
+ const struct bpf_diag_mod_target *origin)
+{
+ struct bpf_diag_history_event event = {
+ .insn_idx = insn_idx,
+ .kind = BPF_DIAG_HISTORY_MOD,
+ .mod = {
+ .target = target,
+ .reason = reason,
+ },
+ };
+
+ if (old_reg)
+ diag_snapshot_reg(&event.mod.old, old_reg);
+ if (new_reg)
+ diag_snapshot_reg(&event.mod.new, new_reg);
+ if (old_reg && new_reg &&
+ (reason == BPF_DIAG_MOD_WRITE || reason == BPF_DIAG_MOD_SPILL) &&
+ diag_snapshot_eq(&event.mod.old, &event.mod.new))
+ return;
+ if (origin) {
+ event.mod.origin = *origin;
+ event.mod.origin_valid = true;
+ } else if (diag_mod_insn_origin(env, insn_idx, &target, &event.mod.origin)) {
+ event.mod.origin_valid = true;
+ }
+
+ diag_append_history(env, &event);
+}
+
+static struct bpf_func_state *diag_func_state(struct bpf_verifier_env *env, u32 frameno)
+{
+ struct bpf_verifier_state *vstate = env->cur_state;
+ int frame;
+
+ for (frame = 0; frame <= vstate->curframe; frame++) {
+ if (vstate->frame[frame]->frameno == frameno)
+ return vstate->frame[frame];
+ }
+ return NULL;
+}
+
+static struct bpf_reg_state *target_to_reg(struct bpf_verifier_env *env,
+ const struct bpf_diag_mod_target *target)
+{
+ struct bpf_func_state *state = diag_func_state(env, target->frameno);
+
+ if (!state)
+ return NULL;
+
+ switch (target->kind) {
+ case BPF_DIAG_MOD_TARGET_REG:
+ if (target->regno >= MAX_BPF_REG)
+ return NULL;
+ return &state->regs[target->regno];
+ case BPF_DIAG_MOD_TARGET_STACK_ARG:
+ if (target->stack_arg >= state->out_stack_arg_cnt)
+ return NULL;
+ return &state->stack_arg_regs[target->stack_arg];
+ case BPF_DIAG_MOD_TARGET_STACK_SLOT:
+ if (target->spi >= state->allocated_stack / BPF_REG_SIZE)
+ return NULL;
+ return &state->stack[target->spi].spilled_ptr;
+ default:
+ return NULL;
+ }
+}
+
+static bool reg_to_target(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
+ struct bpf_diag_mod_target *target)
+{
+ struct bpf_verifier_state *vstate = env->cur_state;
+ unsigned long addr = (unsigned long)reg;
+ int frame;
+
+ for (frame = 0; frame <= vstate->curframe; frame++) {
+ struct bpf_func_state *state = vstate->frame[frame];
+ unsigned long start, end;
+ u32 nslots = state->allocated_stack / BPF_REG_SIZE;
+ int spi;
+
+ start = (unsigned long)state->regs;
+ end = (unsigned long)(state->regs + MAX_BPF_REG);
+ if (addr >= start && addr < end) {
+ *target = bpf_diag_reg_target(state->frameno, reg - state->regs);
+ return true;
+ }
+
+ start = (unsigned long)state->stack_arg_regs;
+ end = (unsigned long)(state->stack_arg_regs + state->out_stack_arg_cnt);
+ if (state->out_stack_arg_cnt && addr >= start && addr < end) {
+ *target = bpf_diag_stack_arg_target(state->frameno,
+ reg - state->stack_arg_regs);
+ return true;
+ }
+
+ start = (unsigned long)state->stack;
+ end = (unsigned long)(state->stack + nslots);
+ if (nslots && addr >= start && addr < end) {
+ spi = ((const char *)reg - (const char *)state->stack) /
+ sizeof(*state->stack);
+ *target = bpf_diag_stack_slot_target(state->frameno, spi);
+ return true;
+ }
+ }
+ return false;
+}
+
+void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
+ const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason)
+{
+ struct bpf_diag *diag = diag_env(env);
+
+ if (!diag)
+ return;
+ diag->mod.active = reg_to_target(env, reg, &diag->mod.target);
+ if (!diag->mod.active)
+ return;
+ diag->mod.target_reg_snapshot = *reg;
+ diag->mod.insn_idx = env->insn_idx;
+ diag->mod.reason = reason;
+ diag->mod.origin_valid = origin && reg_to_target(env, origin, &diag->mod.origin);
+}
+
+void bpf_diag_mod_end(struct bpf_verifier_env *env)
+{
+ struct bpf_diag *diag = diag_env(env);
+ const struct bpf_reg_state *new_reg;
+
+ if (!diag || !diag->mod.active)
+ return;
+ diag->mod.active = false;
+ /*
+ * Resolve the target again because the enclosing function state's stack
+ * may have been reallocated while the modification was in progress.
+ */
+ new_reg = target_to_reg(env, &diag->mod.target);
+ if (!new_reg)
+ return;
+ bpf_diag_record_mod(env, diag->mod.insn_idx, diag->mod.target, diag->mod.reason,
+ &diag->mod.target_reg_snapshot, new_reg,
+ diag->mod.origin_valid ? &diag->mod.origin : NULL);
+}
+
+void bpf_diag_record_scrub(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
+ enum bpf_diag_mod_reason reason)
+{
+ struct bpf_diag_mod_target target;
+
+ if (!diag_env(env) || reg->type == NOT_INIT || !reg_to_target(env, reg, &target))
+ return;
+ bpf_diag_record_mod(env, env->insn_idx, target, reason, reg, NULL, NULL);
+}
+
+void bpf_diag_record_scrub_stack(struct bpf_verifier_env *env, u32 frameno, s16 min_off,
+ s16 max_off, enum bpf_diag_mod_reason reason)
+{
+ bpf_diag_record_mod(env, env->insn_idx,
+ bpf_diag_stack_range_target(frameno, min_off, max_off), reason,
+ NULL, NULL, NULL);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 9cc6b4747a06..8785f8d9a9ca 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -7,7 +7,79 @@
#include <linux/compiler_attributes.h>
#include <linux/types.h>
+struct bpf_reg_state;
struct bpf_verifier_env;
+struct btf;
+
+enum bpf_diag_mod_reason {
+ BPF_DIAG_MOD_WRITE,
+ BPF_DIAG_MOD_SPILL,
+ BPF_DIAG_MOD_VAR_WRITE,
+ BPF_DIAG_MOD_REF_RELEASE,
+ BPF_DIAG_MOD_PKT_DATA_CHANGE,
+ BPF_DIAG_MOD_NON_OWN_REF,
+ BPF_DIAG_MOD_CALLER_SAVED,
+};
+
+enum bpf_diag_mod_target_kind {
+ BPF_DIAG_MOD_TARGET_NONE,
+ BPF_DIAG_MOD_TARGET_REG,
+ BPF_DIAG_MOD_TARGET_STACK_ARG,
+ BPF_DIAG_MOD_TARGET_STACK_SLOT,
+ BPF_DIAG_MOD_TARGET_STACK_RANGE,
+};
+
+struct bpf_diag_mod_target {
+ union {
+ struct {
+ s16 min_off;
+ s16 max_off;
+ } range;
+ u16 spi;
+ u8 regno;
+ u8 stack_arg;
+ };
+ u8 frameno;
+ u8 kind;
+};
+
+static inline struct bpf_diag_mod_target bpf_diag_reg_target(u32 frameno, u8 regno)
+{
+ return (struct bpf_diag_mod_target){
+ .frameno = frameno,
+ .kind = BPF_DIAG_MOD_TARGET_REG,
+ .regno = regno,
+ };
+}
+
+static inline struct bpf_diag_mod_target bpf_diag_stack_arg_target(u32 frameno, u8 slot)
+{
+ return (struct bpf_diag_mod_target){
+ .frameno = frameno,
+ .kind = BPF_DIAG_MOD_TARGET_STACK_ARG,
+ .stack_arg = slot,
+ };
+}
+
+static inline struct bpf_diag_mod_target bpf_diag_stack_slot_target(u32 frameno, u16 spi)
+{
+ return (struct bpf_diag_mod_target){
+ .frameno = frameno,
+ .kind = BPF_DIAG_MOD_TARGET_STACK_SLOT,
+ .spi = spi,
+ };
+}
+
+static inline struct bpf_diag_mod_target bpf_diag_stack_range_target(u32 frameno, s16 min_off,
+ s16 max_off)
+{
+ return (struct bpf_diag_mod_target){
+ .frameno = frameno,
+ .kind = BPF_DIAG_MOD_TARGET_STACK_RANGE,
+ .range.min_off = min_off,
+ .range.max_off = max_off,
+ };
+}
bool bpf_diag_enabled(const struct bpf_verifier_env *env);
int bpf_diag_init(struct bpf_verifier_env *env);
@@ -15,6 +87,7 @@ char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size);
const char *bpf_diag_vfmt(struct bpf_verifier_env *env, const char *fmt, va_list args)
__printf(2, 0);
const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+const char *bpf_diag_fmt_btf_type(struct bpf_verifier_env *env, const struct btf *btf, u32 type_id);
u32 bpf_diag_event_log_pos(struct bpf_verifier_env *env);
void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos);
void bpf_diag_free(struct bpf_verifier_env *env);
@@ -23,5 +96,12 @@ void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
const char *fmt, ...) __printf(4, 5);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
+void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
+ const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
+void bpf_diag_mod_end(struct bpf_verifier_env *env);
+void bpf_diag_record_scrub(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
+ enum bpf_diag_mod_reason reason);
+void bpf_diag_record_scrub_stack(struct bpf_verifier_env *env, u32 frameno, s16 min_off,
+ s16 max_off, enum bpf_diag_mod_reason reason);
#endif /* __BPF_DIAGNOSTICS_H */
diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index b740fa73ee26..589770ca3d3a 100644
--- a/kernel/bpf/log.c
+++ b/kernel/bpf/log.c
@@ -615,17 +615,6 @@ static void print_scalar_ranges(struct bpf_verifier_env *env,
}
}
-static bool type_is_map_ptr(enum bpf_reg_type t) {
- switch (base_type(t)) {
- case CONST_PTR_TO_MAP:
- case PTR_TO_MAP_KEY:
- case PTR_TO_MAP_VALUE:
- return true;
- default:
- return false;
- }
-}
-
/*
* _a stands for append, was shortened to avoid multiline statements below.
* This macro is used to output a comma separated list of attributes.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2e915292265b..ed8a239a964d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1792,6 +1792,17 @@ static const int caller_saved[CALLER_SAVED_REGS] = {
BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
};
+static void bpf_diag_record_caller_saved(struct bpf_verifier_env *env,
+ struct bpf_reg_state *regs)
+{
+ int i;
+
+ for (i = 1; i < CALLER_SAVED_REGS; i++) {
+ bpf_diag_record_scrub(env, ®s[caller_saved[i]],
+ BPF_DIAG_MOD_CALLER_SAVED);
+ }
+}
+
/* This helper doesn't clear reg->id */
static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
@@ -3341,6 +3352,7 @@ static void save_register_state(struct bpf_verifier_env *env,
{
int i;
+ bpf_diag_mod_begin(env, &state->stack[spi].spilled_ptr, reg, BPF_DIAG_MOD_SPILL);
state->stack[spi].spilled_ptr = *reg;
for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
@@ -3349,6 +3361,8 @@ static void save_register_state(struct bpf_verifier_env *env,
/* size < 8 bytes spill */
for (; i; i--)
mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]);
+
+ bpf_diag_mod_end(env);
}
static bool is_bpf_st_mem(struct bpf_insn *insn)
@@ -3485,6 +3499,9 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
} else {
u8 type = STACK_MISC;
+ if (bpf_is_spilled_reg(&state->stack[spi]))
+ bpf_diag_record_scrub(env, &state->stack[spi].spilled_ptr,
+ BPF_DIAG_MOD_WRITE);
scrub_special_slot(state, spi);
/* when we zero initialize stack slots mark them as such */
@@ -3645,6 +3662,8 @@ static int check_stack_write_var_off(struct bpf_verifier_env *env,
if (err)
return err;
}
+ bpf_diag_record_scrub_stack(env, state->frameno, min_off, max_off,
+ BPF_DIAG_MOD_VAR_WRITE);
return 0;
}
@@ -3737,6 +3756,12 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
mark_stack_slot_scratched(env, spi);
check_fastcall_stack_contract(env, state, env->insn_idx, off);
+ /*
+ * Refine the in-progress load record's origin to the source stack slot.
+ */
+ if (dst_regno >= 0)
+ bpf_diag_mod_begin(env, &state->regs[dst_regno], reg, BPF_DIAG_MOD_WRITE);
+
if (bpf_is_spilled_reg(®_state->stack[spi])) {
u8 spill_size = 1;
@@ -4031,14 +4056,17 @@ static int check_stack_arg_write(struct bpf_verifier_env *env, struct bpf_func_s
if (spi + 1 > subprog->max_out_stack_arg_cnt)
subprog->max_out_stack_arg_cnt = spi + 1;
+ arg = &state->stack_arg_regs[spi];
+ bpf_diag_mod_begin(env, arg, value_reg, BPF_DIAG_MOD_WRITE);
+
if (value_reg) {
state->stack_arg_regs[spi] = *value_reg;
} else {
/* BPF_ST: store immediate, treat as scalar */
- arg = &state->stack_arg_regs[spi];
arg->type = SCALAR_VALUE;
__mark_reg_known(arg, env->prog->insnsi[env->insn_idx].imm);
}
+ bpf_diag_mod_end(env);
state->no_stack_arg_load = true;
return bpf_push_jmp_history(env, env->cur_state,
INSN_F_STACK_ARG_ACCESS, spi, 0, 0);
@@ -4071,7 +4099,9 @@ static int check_stack_arg_read(struct bpf_verifier_env *env, struct bpf_func_st
caller = vstate->frame[vstate->curframe - 1];
arg = &caller->stack_arg_regs[spi];
cur = vstate->frame[vstate->curframe];
+ bpf_diag_mod_begin(env, &cur->regs[dst_regno], arg, BPF_DIAG_MOD_WRITE);
cur->regs[dst_regno] = *arg;
+ bpf_diag_mod_end(env);
return bpf_push_jmp_history(env, env->cur_state,
INSN_F_STACK_ARG_ACCESS, spi, 0, 0);
}
@@ -6391,15 +6421,19 @@ static int check_load_mem(struct bpf_verifier_env *env, struct bpf_insn *insn,
src_reg_type = regs[insn->src_reg].type;
- /* Check if (src_reg + off) is readable. The state of dst_reg will be
- * updated by this call.
+ /*
+ * check_stack_read_fixed_off() may refine the modification's origin to
+ * the source stack slot.
*/
+ bpf_diag_mod_begin(env, ®s[insn->dst_reg], NULL, BPF_DIAG_MOD_WRITE);
err = check_mem_access(env, env->insn_idx, regs + insn->src_reg, argno_from_reg(insn->src_reg), insn->off,
BPF_SIZE(insn->code), BPF_READ, insn->dst_reg,
strict_alignment_once, is_ldsx);
err = err ?: save_aux_ptr_type(env, src_reg_type,
allow_trust_mismatch);
err = err ?: reg_bounds_sanity_check(env, ®s[insn->dst_reg], ctx);
+ if (!err)
+ bpf_diag_mod_end(env);
return err;
}
@@ -8902,13 +8936,18 @@ static int check_func_proto(const struct bpf_func_proto *fn, struct bpf_call_arg
*/
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
+ struct bpf_stack_state *stack;
struct bpf_func_state *state;
struct bpf_reg_state *reg;
- bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
- if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
- mark_reg_invalid(env, reg);
- }));
+ bpf_for_each_reg_in_vstate_mask(
+ env->cur_state, state, reg, stack, 1 << STACK_SPILL, ({
+ if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg)) {
+ bpf_diag_record_scrub(env, reg, BPF_DIAG_MOD_PKT_DATA_CHANGE);
+ mark_reg_invalid(env, reg);
+ }
+ }))
+ ;
}
enum {
@@ -9012,22 +9051,39 @@ static int release_reference(struct bpf_verifier_env *env, int id)
return -EINVAL;
}
- bpf_for_each_reg_in_vstate_mask(vstate, state, reg, stack, mask, ({
- if (reg->id != id && reg->parent_id != id)
- continue;
+ bpf_for_each_reg_in_vstate_mask(
+ vstate, state, reg, stack, mask, ({
+ if (reg->id != id && reg->parent_id != id)
+ continue;
- /* Free objects derived from the current object */
- if (reg->parent_id == id) {
- err = idstack_push(idstack, reg->id);
- if (err)
- return err;
- }
+ /* Free objects derived from the current object */
+ if (reg->parent_id == id) {
+ err = idstack_push(idstack, reg->id);
+ if (err)
+ return err;
+ }
- if (!stack || stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL)
- mark_reg_invalid(env, reg);
- else if (stack->slot_type[BPF_REG_SIZE - 1] == STACK_DYNPTR)
- invalidate_dynptr(env, stack);
- }));
+ /*
+ * A dynptr occupies two stack slots that invalidate_dynptr()
+ * clears together. Record both scrubs before invalidating it.
+ */
+ if (stack && stack->slot_type[BPF_REG_SIZE - 1] == STACK_DYNPTR) {
+ struct bpf_stack_state *dyn_stack = stack;
+
+ if (reg->dynptr.first_slot)
+ dyn_stack--;
+ bpf_diag_record_scrub(env, &dyn_stack[0].spilled_ptr,
+ BPF_DIAG_MOD_REF_RELEASE);
+ bpf_diag_record_scrub(env, &dyn_stack[1].spilled_ptr,
+ BPF_DIAG_MOD_REF_RELEASE);
+ invalidate_dynptr(env, dyn_stack);
+ continue;
+ }
+ bpf_diag_record_scrub(env, reg, BPF_DIAG_MOD_REF_RELEASE);
+ if (!stack || stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL)
+ mark_reg_invalid(env, reg);
+ }))
+ ;
}
return 0;
@@ -9035,13 +9091,18 @@ static int release_reference(struct bpf_verifier_env *env, int id)
static void invalidate_non_owning_refs(struct bpf_verifier_env *env)
{
- struct bpf_func_state *unused;
+ struct bpf_stack_state *stack;
+ struct bpf_func_state *state;
struct bpf_reg_state *reg;
- bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
- if (type_is_non_owning_ref(reg->type))
- mark_reg_invalid(env, reg);
- }));
+ bpf_for_each_reg_in_vstate_mask(
+ env->cur_state, state, reg, stack, 1 << STACK_SPILL, ({
+ if (type_is_non_owning_ref(reg->type)) {
+ bpf_diag_record_scrub(env, reg, BPF_DIAG_MOD_NON_OWN_REF);
+ mark_reg_invalid(env, reg);
+ }
+ }))
+ ;
}
static void invalidate_rcu_protected_refs(struct bpf_verifier_env *env)
@@ -10442,12 +10503,14 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return err;
/* reset caller saved regs */
+ bpf_diag_record_caller_saved(env, regs);
for (i = 0; i < CALLER_SAVED_REGS; i++) {
bpf_mark_reg_not_init(env, ®s[caller_saved[i]]);
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
}
invalidate_outgoing_stack_args(env, cur_func(env));
+ bpf_diag_mod_begin(env, ®s[BPF_REG_0], NULL, BPF_DIAG_MOD_WRITE);
/* update return register (already marked as written above) */
ret_type = fn->ret_type;
ret_flag = type_flag(ret_type);
@@ -10630,6 +10693,8 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
if (err)
return err;
+ bpf_diag_mod_end(env);
+
err = check_map_func_compatibility(env, meta.map.ptr, func_id);
if (err)
return err;
@@ -13142,6 +13207,8 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
}
}
+ bpf_diag_record_caller_saved(env, regs);
+ bpf_diag_mod_begin(env, ®s[BPF_REG_0], NULL, BPF_DIAG_MOD_WRITE);
for (i = 0; i < CALLER_SAVED_REGS; i++) {
u32 regno = caller_saved[i];
@@ -13293,6 +13360,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
caller_info->stack_arg_cnt = stack_arg_cnt;
}
+ /*
+ * Record R0 before process_iter_next_call() snapshots the alternate
+ * iterator path's diagnostic position.
+ */
+ bpf_diag_mod_end(env);
+
if (bpf_is_iter_next_kfunc(&meta)) {
err = process_iter_next_call(env, insn_idx, &meta);
if (err)
@@ -14935,6 +15008,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
u8 opcode = BPF_OP(insn->code);
int err;
+ bpf_diag_mod_begin(env, ®s[insn->dst_reg], NULL, BPF_DIAG_MOD_WRITE);
+
if (opcode == BPF_END || opcode == BPF_NEG) {
/* check src operand */
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
@@ -15108,7 +15183,12 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
return err;
}
- return reg_bounds_sanity_check(env, ®s[insn->dst_reg], "alu");
+ err = reg_bounds_sanity_check(env, ®s[insn->dst_reg], "alu");
+ if (err)
+ return err;
+
+ bpf_diag_mod_end(env);
+ return 0;
}
static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 06/16] bpf: Track verifier reference diagnostic events
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (4 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 07/16] bpf: Track verifier context " Kumar Kartikeya Dwivedi
` (10 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Add reference acquire and release events to diagnostic history so Resource
Lifetime Safety reports can show the lifetime of a specific reference id along
the path.
Record acquisitions after the verifier assigns the reference id. Record
releases only after release_reference_nomark() succeeds, including the
kptr_xchg RCU conversion path and owning-to-non-owning conversion path that
consume an owning reference.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 28 ++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 2 ++
kernel/bpf/verifier.c | 32 +++++++++++++++++++++++++-------
3 files changed, 55 insertions(+), 7 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 460bb83ae33d..0143ffe6fa03 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -47,6 +47,8 @@ struct bpf_diag_reg_snapshot {
enum bpf_diag_history_kind {
BPF_DIAG_HISTORY_BRANCH,
BPF_DIAG_HISTORY_MOD,
+ BPF_DIAG_HISTORY_REF_ACQUIRE,
+ BPF_DIAG_HISTORY_REF_RELEASE,
};
struct bpf_diag_history_event {
@@ -64,6 +66,9 @@ struct bpf_diag_history_event {
u8 reason;
bool origin_valid;
} mod;
+ struct {
+ u32 ref_id;
+ } ref;
};
};
@@ -939,3 +944,26 @@ void bpf_diag_record_scrub_stack(struct bpf_verifier_env *env, u32 frameno, s16
bpf_diag_stack_range_target(frameno, min_off, max_off), reason,
NULL, NULL, NULL);
}
+
+static void diag_record_ref(struct bpf_verifier_env *env, u32 insn_idx, u8 kind, u32 ref_id)
+{
+ struct bpf_diag_history_event event = {
+ .insn_idx = insn_idx,
+ .kind = kind,
+ .ref = {
+ .ref_id = ref_id,
+ },
+ };
+
+ diag_append_history(env, &event);
+}
+
+void bpf_diag_record_ref_acquire(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id)
+{
+ diag_record_ref(env, insn_idx, BPF_DIAG_HISTORY_REF_ACQUIRE, ref_id);
+}
+
+void bpf_diag_record_ref_release(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id)
+{
+ diag_record_ref(env, insn_idx, BPF_DIAG_HISTORY_REF_RELEASE, ref_id);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 8785f8d9a9ca..40fe161525b9 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -103,5 +103,7 @@ void bpf_diag_record_scrub(struct bpf_verifier_env *env, const struct bpf_reg_st
enum bpf_diag_mod_reason reason);
void bpf_diag_record_scrub_stack(struct bpf_verifier_env *env, u32 frameno, s16 min_off,
s16 max_off, enum bpf_diag_mod_reason reason);
+void bpf_diag_record_ref_acquire(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id);
+void bpf_diag_record_ref_release(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id);
#endif /* __BPF_DIAGNOSTICS_H */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ed8a239a964d..4f3416700ad7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -205,7 +205,8 @@ struct bpf_verifier_stack_elem {
#define BPF_PRIV_STACK_MIN_SIZE 64
static int acquire_reference(struct bpf_verifier_env *env, int insn_idx, int parent_id);
-static int release_reference_nomark(struct bpf_verifier_state *state, int id);
+static int __release_reference_nomark(struct bpf_verifier_state *state, int id);
+static int release_reference_nomark(struct bpf_verifier_env *env, int id);
static int release_reference(struct bpf_verifier_env *env, int id);
static void invalidate_non_owning_refs(struct bpf_verifier_env *env);
static void invalidate_rcu_protected_refs(struct bpf_verifier_env *env);
@@ -1419,6 +1420,7 @@ static int acquire_reference(struct bpf_verifier_env *env, int insn_idx, int par
s->type = REF_TYPE_PTR;
s->id = ++env->id_gen;
s->parent_id = parent_id;
+ bpf_diag_record_ref_acquire(env, insn_idx, s->id);
return s->id;
}
@@ -8976,7 +8978,7 @@ static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range
reg->range = AT_PKT_END;
}
-static int release_reference_nomark(struct bpf_verifier_state *state, int id)
+static int __release_reference_nomark(struct bpf_verifier_state *state, int id)
{
int i;
@@ -8991,6 +8993,16 @@ static int release_reference_nomark(struct bpf_verifier_state *state, int id)
return -EINVAL;
}
+static int release_reference_nomark(struct bpf_verifier_env *env, int id)
+{
+ int err;
+
+ err = __release_reference_nomark(env->cur_state, id);
+ if (!err)
+ bpf_diag_record_ref_release(env, env->insn_idx, id);
+ return err;
+}
+
static int idstack_push(struct bpf_idmap *idmap, u32 id)
{
int i;
@@ -9033,8 +9045,10 @@ static int release_reference(struct bpf_verifier_env *env, int id)
if (err)
return err;
- if (find_reference_state(vstate, id))
- WARN_ON_ONCE(release_reference_nomark(vstate, id));
+ if (find_reference_state(vstate, id)) {
+ err = release_reference_nomark(env, id);
+ WARN_ON_ONCE(err);
+ }
while ((id = idstack_pop(idstack))) {
/*
@@ -9126,7 +9140,9 @@ static int ref_convert_alloc_rcu_protected(struct bpf_verifier_env *env, u32 id)
struct bpf_reg_state *reg;
int err;
- err = release_reference_nomark(env->cur_state, id);
+ err = release_reference_nomark(env, id);
+ if (err)
+ return err;
bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
if (reg->id != id)
@@ -11670,8 +11686,10 @@ static void ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 id)
{
struct bpf_func_state *unused;
struct bpf_reg_state *reg;
+ int err;
- WARN_ON_ONCE(release_reference_nomark(env->cur_state, id));
+ err = release_reference_nomark(env, id);
+ WARN_ON_ONCE(err);
bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
if (reg->id == id) {
@@ -15803,7 +15821,7 @@ static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
* No one could have freed the reference state before
* doing the NULL check.
*/
- WARN_ON_ONCE(release_reference_nomark(vstate, id));
+ WARN_ON_ONCE(__release_reference_nomark(vstate, id));
bpf_for_each_reg_in_vstate(vstate, state, reg, ({
mark_ptr_or_null_reg(state, reg, id, is_null);
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 07/16] bpf: Track verifier context diagnostic events
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (5 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 06/16] bpf: Track verifier reference " Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 08/16] bpf: Report Register Type Safety errors Kumar Kartikeya Dwivedi
` (9 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Record verifier context transitions in the diagnostic history so later reports
can anchor causal paths to the critical section that made an operation invalid.
This covers lock, IRQ, RCU, and preempt regions without adding any new
verifier error reports. Category-specific commits decide where those recorded
events should be rendered.
Use context depth when selecting scoped history so nested regions anchor at the
outer active region, and fall back to the earliest retained event when the
matching entry was pruned.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 39 +++++++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 12 ++++++++++++
kernel/bpf/verifier.c | 28 +++++++++++++++++++++++-----
3 files changed, 74 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 0143ffe6fa03..823e0a7a0638 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -49,6 +49,7 @@ enum bpf_diag_history_kind {
BPF_DIAG_HISTORY_MOD,
BPF_DIAG_HISTORY_REF_ACQUIRE,
BPF_DIAG_HISTORY_REF_RELEASE,
+ BPF_DIAG_HISTORY_CONTEXT,
};
struct bpf_diag_history_event {
@@ -69,6 +70,11 @@ struct bpf_diag_history_event {
struct {
u32 ref_id;
} ref;
+ struct {
+ u32 depth;
+ u8 kind;
+ bool enter;
+ } ctx;
};
};
@@ -335,6 +341,19 @@ void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos)
log->cnt = pos;
}
+u32 bpf_diag_irq_depth(const struct bpf_verifier_state *state)
+{
+ u32 depth = 0;
+ int i;
+
+ for (i = 0; i < state->acquired_refs; i++) {
+ if (state->refs[i].type == REF_TYPE_IRQ)
+ depth++;
+ }
+
+ return depth;
+}
+
static void diag_append_history(struct bpf_verifier_env *env,
const struct bpf_diag_history_event *event)
{
@@ -967,3 +986,23 @@ void bpf_diag_record_ref_release(struct bpf_verifier_env *env, u32 insn_idx, u32
{
diag_record_ref(env, insn_idx, BPF_DIAG_HISTORY_REF_RELEASE, ref_id);
}
+
+void bpf_diag_record_context(struct bpf_verifier_env *env, u32 insn_idx,
+ enum bpf_diag_context_kind ctx_kind, bool enter, u32 depth)
+{
+ /*
+ * Keep leave events so context rendering can stop at a depth-zero exit
+ * and show nested-region depth accurately for the active path.
+ */
+ struct bpf_diag_history_event event = {
+ .insn_idx = insn_idx,
+ .kind = BPF_DIAG_HISTORY_CONTEXT,
+ .ctx = {
+ .kind = ctx_kind,
+ .enter = enter,
+ .depth = depth,
+ },
+ };
+
+ diag_append_history(env, &event);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 40fe161525b9..0cf5427a1a1b 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -9,6 +9,7 @@
struct bpf_reg_state;
struct bpf_verifier_env;
+struct bpf_verifier_state;
struct btf;
enum bpf_diag_mod_reason {
@@ -81,6 +82,14 @@ static inline struct bpf_diag_mod_target bpf_diag_stack_range_target(u32 frameno
};
}
+enum bpf_diag_context_kind {
+ BPF_DIAG_CONTEXT_NONE,
+ BPF_DIAG_CONTEXT_RCU,
+ BPF_DIAG_CONTEXT_PREEMPT,
+ BPF_DIAG_CONTEXT_IRQ,
+ BPF_DIAG_CONTEXT_LOCK,
+};
+
bool bpf_diag_enabled(const struct bpf_verifier_env *env);
int bpf_diag_init(struct bpf_verifier_env *env);
char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size);
@@ -90,6 +99,7 @@ const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...) __p
const char *bpf_diag_fmt_btf_type(struct bpf_verifier_env *env, const struct btf *btf, u32 type_id);
u32 bpf_diag_event_log_pos(struct bpf_verifier_env *env);
void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos);
+u32 bpf_diag_irq_depth(const struct bpf_verifier_state *state);
void bpf_diag_free(struct bpf_verifier_env *env);
void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
const char *problem);
@@ -105,5 +115,7 @@ void bpf_diag_record_scrub_stack(struct bpf_verifier_env *env, u32 frameno, s16
s16 max_off, enum bpf_diag_mod_reason reason);
void bpf_diag_record_ref_acquire(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id);
void bpf_diag_record_ref_release(struct bpf_verifier_env *env, u32 insn_idx, u32 ref_id);
+void bpf_diag_record_context(struct bpf_verifier_env *env, u32 insn_idx,
+ enum bpf_diag_context_kind ctx_kind, bool enter, u32 depth);
#endif /* __BPF_DIAGNOSTICS_H */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 4f3416700ad7..a32f360d0f00 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1046,7 +1046,7 @@ static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_s
}
static int acquire_irq_state(struct bpf_verifier_env *env, int insn_idx);
-static int release_irq_state(struct bpf_verifier_state *state, int id);
+static int release_irq_state(struct bpf_verifier_env *env, int id);
static int mark_stack_slot_irq_flag(struct bpf_verifier_env *env,
struct bpf_call_arg_meta *meta,
@@ -1105,7 +1105,7 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
return -EINVAL;
}
- err = release_irq_state(env->cur_state, st->id);
+ err = release_irq_state(env, st->id);
WARN_ON_ONCE(err && err != -EACCES);
if (err) {
int insn_idx = 0;
@@ -1440,6 +1440,8 @@ static int acquire_lock_state(struct bpf_verifier_env *env, int insn_idx, enum r
state->active_locks++;
state->active_lock_id = id;
state->active_lock_ptr = ptr;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_LOCK, true,
+ state->active_locks);
return 0;
}
@@ -1455,6 +1457,8 @@ static int acquire_irq_state(struct bpf_verifier_env *env, int insn_idx)
s->id = ++env->id_gen;
state->active_irq_id = s->id;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_IRQ, true,
+ bpf_diag_irq_depth(state));
return s->id;
}
@@ -1496,8 +1500,9 @@ static bool reg_is_referenced(struct bpf_verifier_env *env, const struct bpf_reg
return find_reference_state(env->cur_state, reg->id);
}
-static int release_lock_state(struct bpf_verifier_state *state, int type, int id, void *ptr)
+static int release_lock_state(struct bpf_verifier_env *env, int type, int id, void *ptr)
{
+ struct bpf_verifier_state *state = env->cur_state;
void *prev_ptr = NULL;
u32 prev_id = 0;
int i;
@@ -1510,6 +1515,8 @@ static int release_lock_state(struct bpf_verifier_state *state, int type, int id
/* Reassign active lock (id, ptr). */
state->active_lock_id = prev_id;
state->active_lock_ptr = prev_ptr;
+ bpf_diag_record_context(env, env->insn_idx, BPF_DIAG_CONTEXT_LOCK,
+ false, state->active_locks);
return 0;
}
if (state->refs[i].type & REF_TYPE_LOCK_MASK) {
@@ -1520,8 +1527,9 @@ static int release_lock_state(struct bpf_verifier_state *state, int type, int id
return -EINVAL;
}
-static int release_irq_state(struct bpf_verifier_state *state, int id)
+static int release_irq_state(struct bpf_verifier_env *env, int id)
{
+ struct bpf_verifier_state *state = env->cur_state;
u32 prev_id = 0;
int i;
@@ -1534,6 +1542,8 @@ static int release_irq_state(struct bpf_verifier_state *state, int id)
if (state->refs[i].id == id) {
release_reference_state(state, i);
state->active_irq_id = prev_id;
+ bpf_diag_record_context(env, env->insn_idx, BPF_DIAG_CONTEXT_IRQ,
+ false, bpf_diag_irq_depth(state));
return 0;
} else {
prev_id = state->refs[i].id;
@@ -7142,7 +7152,7 @@ static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state
verbose(env, "%s_unlock cannot be out of order\n", lock_str);
return -EINVAL;
}
- if (release_lock_state(cur, type, reg->id, ptr)) {
+ if (release_lock_state(env, type, reg->id, ptr)) {
verbose(env, "%s_unlock of different lock\n", lock_str);
return -EINVAL;
}
@@ -13155,22 +13165,30 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (rcu_lock) {
env->cur_state->active_rcu_locks++;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_RCU, true,
+ env->cur_state->active_rcu_locks);
} else if (rcu_unlock) {
if (env->cur_state->active_rcu_locks == 0) {
verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
return -EINVAL;
}
env->cur_state->active_rcu_locks--;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_RCU, false,
+ env->cur_state->active_rcu_locks);
if (!in_rcu_cs(env))
invalidate_rcu_protected_refs(env);
} else if (preempt_disable) {
env->cur_state->active_preempt_locks++;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_PREEMPT, true,
+ env->cur_state->active_preempt_locks);
} else if (preempt_enable) {
if (env->cur_state->active_preempt_locks == 0) {
verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
return -EINVAL;
}
env->cur_state->active_preempt_locks--;
+ bpf_diag_record_context(env, insn_idx, BPF_DIAG_CONTEXT_PREEMPT, false,
+ env->cur_state->active_preempt_locks);
if (!in_rcu_cs(env))
invalidate_rcu_protected_refs(env);
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 08/16] bpf: Report Register Type Safety errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (6 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 07/16] bpf: Track verifier context " Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 09/16] bpf: Report Memory Safety bounds errors Kumar Kartikeya Dwivedi
` (8 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Augment selected register-state verifier failures with Register Type Safety
reports. The existing verbose verifier messages remain in place; the new
reports add reason, source context, causal path, and suggestions.
Cover invalid pointer dereferences, unreadable registers, missing outgoing
stack arguments for bpf2bpf and kfunc calls, and rejected pointer arithmetic.
Use scoped diagnostic history so reports start from the latest relevant value
change and then show later branch outcomes.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 898 ++++++++++++++++++
kernel/bpf/diagnostics.h | 18 +
kernel/bpf/verifier.c | 128 ++-
.../selftests/bpf/progs/verifier_uninit.c | 1 +
4 files changed, 1030 insertions(+), 15 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 823e0a7a0638..53529475b0ec 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2026 Meta Platforms, Inc. and affiliates.
+#include <linux/bitmap.h>
#include <linux/bpf.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
@@ -25,6 +26,7 @@
#define VERIFIER_LIMIT "Verifier Limit"
#define BPF_DIAG_TEXT_WIDTH 100
+#define BPF_DIAG_TEXT_INDENT " "
#define BPF_DIAG_MSG_LEN 512
#define BPF_DIAG_CONTEXT 2
#define BPF_DIAG_CONTEXT_CNT (1 + BPF_DIAG_CONTEXT * 2)
@@ -78,6 +80,28 @@ struct bpf_diag_history_event {
};
};
+enum bpf_diag_history_scope {
+ BPF_DIAG_HISTORY_SCOPE_ALL,
+ BPF_DIAG_HISTORY_SCOPE_REG,
+ BPF_DIAG_HISTORY_SCOPE_STACK_ARG,
+ BPF_DIAG_HISTORY_SCOPE_REF,
+ BPF_DIAG_HISTORY_SCOPE_CONTEXT,
+};
+
+struct bpf_diag_history_opts {
+ enum bpf_diag_history_scope scope;
+ u32 frameno;
+ int regno;
+ int stack_arg_slot;
+ u32 ref_id;
+ enum bpf_diag_context_kind ctx_kind;
+ u32 ctx_depth;
+};
+
+static void diag_print_history(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_opts *opts);
+static bool diag_target_matches(const struct bpf_diag_mod_target *event_target,
+ const struct bpf_diag_mod_target *target);
struct disasm_line {
char text[DISASM_LINE_LEN];
int idx;
@@ -390,6 +414,12 @@ static void diag_append_history(struct bpf_verifier_env *env,
log->events[log->cnt++] = *event;
}
+static const struct bpf_diag_history_event *diag_history_event(const struct bpf_diag_log *log,
+ u32 idx)
+{
+ return &log->events[idx];
+}
+
static void diag_print_wrapped_prefixed(struct bpf_verifier_env *env, const char *first_prefix,
const char *next_prefix, const char *text)
{
@@ -425,6 +455,11 @@ static void diag_print_wrapped_prefixed(struct bpf_verifier_env *env, const char
}
}
+static void diag_print_wrapped_text(struct bpf_verifier_env *env, const char *text)
+{
+ diag_print_wrapped_prefixed(env, BPF_DIAG_TEXT_INDENT, BPF_DIAG_TEXT_INDENT, text);
+}
+
static void bpf_diag_format_btf_type(char *buf, size_t size, const struct btf *btf, u32 type_id)
{
size_t len;
@@ -453,6 +488,26 @@ const char *bpf_diag_fmt_btf_type(struct bpf_verifier_env *env, const struct btf
return buf;
}
+static void diag_vprint_indented(struct bpf_verifier_env *env, const char *fmt, va_list args)
+ __printf(2, 0);
+
+static void diag_vprint_indented(struct bpf_verifier_env *env, const char *fmt, va_list args)
+{
+ char *buf;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ buf = kvasprintf(GFP_KERNEL_ACCOUNT, fmt, args);
+ if (!buf) {
+ diag_write(env, "%s<failed to allocate diagnostic text>\n", BPF_DIAG_TEXT_INDENT);
+ return;
+ }
+
+ diag_print_wrapped_text(env, buf);
+ kfree(buf);
+}
+
static int diag_line_width(unsigned int line)
{
int width = 1;
@@ -613,6 +668,47 @@ void bpf_diag_header(struct bpf_verifier_env *env, const char *category, const c
diag_write(env, "\nVerification failed: %s: %c%s\n", category, first, problem + 1);
}
+static void diag_reason(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
+static void diag_suggestion(struct bpf_verifier_env *env, const char *fmt, ...)
+ __printf(2, 3);
+
+static void diag_section(struct bpf_verifier_env *env, const char *title)
+{
+ if (!bpf_diag_enabled(env))
+ return;
+
+ diag_write(env, "\n%s:\n", title);
+}
+
+static void diag_reason(struct bpf_verifier_env *env, const char *fmt, ...)
+{
+ va_list args;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ diag_section(env, "Reason");
+
+ va_start(args, fmt);
+ diag_vprint_indented(env, fmt, args);
+ va_end(args);
+}
+
+static void diag_suggestion(struct bpf_verifier_env *env, const char *fmt, ...)
+{
+ va_list args;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ diag_section(env, "Suggestion");
+
+ va_start(args, fmt);
+ diag_vprint_indented(env, fmt, args);
+ va_end(args);
+ diag_write(env, "\n");
+}
+
static void diag_print_source_annotation(struct bpf_verifier_env *env, int line_width, int indent,
const char *label, const char *msg)
{
@@ -738,6 +834,277 @@ void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *lab
diag_fmt_restore(env, mark);
}
+static u32 diag_current_frameno(const struct bpf_verifier_env *env)
+{
+ return env->cur_state->frame[env->cur_state->curframe]->frameno;
+}
+
+void bpf_diag_register_type(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *problem, const char *reason, const char *suggestion)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_REG,
+ .frameno = diag_current_frameno(env),
+ .regno = regno,
+ };
+
+ bpf_diag_header(env, REGISTER_TYPE_SAFETY, problem);
+ diag_reason(env, "%s", reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s", problem);
+
+ if (regno >= 0)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+const char *bpf_diag_reg_type_plain(struct bpf_verifier_env *env, enum bpf_reg_type type)
+{
+ switch (base_type(type)) {
+ case NOT_INIT:
+ return "an uninitialized value";
+ case SCALAR_VALUE:
+ return "an integer scalar";
+ case PTR_TO_CTX:
+ return "a context pointer";
+ case PTR_TO_STACK:
+ return "a stack pointer";
+ case PTR_TO_MAP_VALUE:
+ if (type_may_be_null(type))
+ return "a nullable map value pointer";
+ return "a map value pointer";
+ case PTR_TO_MEM:
+ if (type_may_be_null(type))
+ return "a nullable memory pointer";
+ return "a memory pointer";
+ case PTR_TO_BTF_ID:
+ if (type_may_be_null(type))
+ return "a nullable kernel object pointer";
+ if (type_is_non_owning_ref(type))
+ return "a borrowed allocated object pointer";
+ if (type_is_ptr_alloc_obj(type))
+ return "an owned allocated object pointer";
+ if (type_flag(type) & PTR_UNTRUSTED)
+ return "an untrusted kernel object pointer";
+ return "a kernel object pointer";
+ default:
+ return reg_type_str(env, type);
+ }
+}
+
+static const char *diag_arg_ordinal(int argno)
+{
+ switch (argno) {
+ case 1:
+ return "first";
+ case 2:
+ return "second";
+ case 3:
+ return "third";
+ case 4:
+ return "fourth";
+ case 5:
+ return "fifth";
+ case 6:
+ return "sixth";
+ case 7:
+ return "seventh";
+ case 8:
+ return "eighth";
+ case 9:
+ return "ninth";
+ case 10:
+ return "tenth";
+ case 11:
+ return "eleventh";
+ case 12:
+ return "twelfth";
+ default:
+ return NULL;
+ }
+}
+
+void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *reg_name, const struct bpf_reg_state *reg,
+ enum bpf_diag_invalid_deref_kind kind, s64 offset)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_REG,
+ .frameno = diag_current_frameno(env),
+ .regno = regno,
+ };
+ const char *type_name = bpf_diag_reg_type_plain(env, reg->type);
+
+ bpf_diag_header(env, REGISTER_TYPE_SAFETY, "invalid dereference");
+
+ switch (kind) {
+ case BPF_DIAG_DEREF_SCALAR:
+ diag_reason(env, "%s is an integer scalar here, not a pointer to memory.",
+ reg_name);
+ break;
+ case BPF_DIAG_DEREF_NULLABLE_PTR:
+ diag_reason(
+ env, "%s may be NULL here (%s). The program could dereference NULL on this path, so the verifier cannot prove this access is safe.",
+ reg_name, type_name);
+ break;
+ case BPF_DIAG_DEREF_MODIFIED_PTR:
+ diag_reason(
+ env, "%s has offset %lld here, but this pointer type must be dereferenced in its original form.",
+ reg_name, offset);
+ break;
+ case BPF_DIAG_DEREF_INVALID_PTR:
+ default:
+ diag_reason(
+ env, "%s has type %s here, which is not valid for this memory access.",
+ reg_name, type_name);
+ break;
+ }
+
+ diag_section(env, "At");
+ if (kind == BPF_DIAG_DEREF_MODIFIED_PTR)
+ bpf_diag_source(env, insn_idx, "error",
+ "dereference requires the original %s pointer", type_name);
+ else
+ bpf_diag_source(env, insn_idx, "error", "invalid dereference of %s (%s)",
+ reg_name, type_name);
+
+ if (regno >= 0)
+ diag_print_history(env, &opts);
+
+ switch (kind) {
+ case BPF_DIAG_DEREF_NULLABLE_PTR:
+ diag_suggestion(
+ env, "Add a NULL check before the access and dereference the pointer only on the non-NULL path.");
+ break;
+ case BPF_DIAG_DEREF_MODIFIED_PTR:
+ diag_suggestion(
+ env, "Preserve the original pointer in another register, or use only offsets this pointer type permits before dereferencing it.");
+ break;
+ case BPF_DIAG_DEREF_SCALAR:
+ case BPF_DIAG_DEREF_INVALID_PTR:
+ default:
+ diag_suggestion(
+ env, "Preserve a pointer-valued register where needed, or reload and revalidate the pointer after scalar arithmetic, helper calls, or other operations that can invalidate it.");
+ break;
+ }
+}
+
+void bpf_diag_unreadable_reg(struct bpf_verifier_env *env, u32 insn_idx, int regno)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_REG,
+ .frameno = diag_current_frameno(env),
+ .regno = regno,
+ };
+ const struct bpf_diag_log *log = diag_event_log(env);
+ struct bpf_diag_mod_target target;
+ bool invalidated = false;
+ int i;
+
+ target = bpf_diag_reg_target(opts.frameno, regno);
+ for (i = log ? log->cnt : 0; i > 0; i--) {
+ const struct bpf_diag_history_event *event = diag_history_event(log, i - 1);
+
+ if (event->kind != BPF_DIAG_HISTORY_MOD ||
+ !diag_target_matches(&event->mod.target, &target))
+ continue;
+ invalidated = event->mod.new.type == NOT_INIT;
+ break;
+ }
+
+ bpf_diag_header(env, REGISTER_TYPE_SAFETY, "unreadable register");
+ if (invalidated)
+ diag_reason(
+ env, "R%d is not readable here. A previous operation invalidated this register, so the verifier cannot use it as an input.",
+ regno);
+ else if (log && !log->dropped)
+ diag_reason(env,
+ "R%d has never been initialized on this path, so the verifier cannot use it as an input.",
+ regno);
+ else
+ diag_reason(
+ env, "R%d is not readable here. It may never have been initialized, or an earlier operation may have invalidated it.",
+ regno);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "R%d is not readable", regno);
+
+ if (regno >= 0)
+ diag_print_history(env, &opts);
+
+ if (invalidated)
+ diag_suggestion(
+ env, "Avoid using the register after it is invalidated, or initialize it again before this instruction.");
+ else if (log && !log->dropped)
+ diag_suggestion(env, "Initialize R%d on every path before this instruction.", regno);
+ else
+ diag_suggestion(
+ env, "Initialize the register on every path, or initialize it again after any operation that invalidates it.");
+}
+
+static int diag_stack_argno(u8 slot)
+{
+ return MAX_BPF_FUNC_REG_ARGS + slot + 1;
+}
+
+static void diag_format_stack_arg(char *buf, size_t size, u8 slot, const char *arg_name)
+{
+ int argno = diag_stack_argno(slot);
+ const char *ordinal = diag_arg_ordinal(argno);
+
+ if (ordinal && arg_name)
+ scnprintf(buf, size, "outgoing stack argument %u (%s argument, %s)", slot + 1,
+ ordinal, arg_name);
+ else if (ordinal)
+ scnprintf(buf, size, "outgoing stack argument %u (%s argument)", slot + 1, ordinal);
+ else if (arg_name)
+ scnprintf(buf, size, "outgoing stack argument %u (%s)", slot + 1, arg_name);
+ else
+ scnprintf(buf, size, "outgoing stack argument %u", slot + 1);
+}
+
+void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int nargs,
+ int stack_arg_slot, const char *callee_name,
+ const char *arg_name)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_STACK_ARG,
+ .frameno = diag_current_frameno(env),
+ .stack_arg_slot = stack_arg_slot,
+ };
+ const char *arg_buf;
+
+ arg_buf = bpf_diag_fmt_buf(env, BPF_DIAG_FMT_BUF_SIZE);
+ if (arg_buf)
+ diag_format_stack_arg((char *)arg_buf, BPF_DIAG_FMT_BUF_SIZE, stack_arg_slot,
+ arg_name);
+ else
+ arg_buf = "";
+ bpf_diag_header(env, REGISTER_TYPE_SAFETY, "missing stack argument");
+ if (callee_name && *callee_name)
+ diag_reason(env,
+ "Function %s expects %d arguments, but %s is not initialized at "
+ "this call.",
+ callee_name, nargs, arg_buf);
+ else
+ diag_reason(env,
+ "The callee expects %d arguments, but %s is not initialized at "
+ "this call.",
+ nargs, arg_buf);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s is not initialized", arg_buf);
+
+ if (stack_arg_slot >= 0)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "Write the outgoing stack argument after any operation that "
+ "may invalidate stored pointer values, and before making this "
+ "call.");
+}
+
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true)
{
struct bpf_diag_history_event event = {
@@ -1006,3 +1373,534 @@ void bpf_diag_record_context(struct bpf_verifier_env *env, u32 insn_idx,
diag_append_history(env, &event);
}
+
+static int diag_history_context_start_idx(const struct bpf_diag_log *log,
+ const struct bpf_diag_history_opts *opts)
+{
+ int i;
+
+ if (!opts->ctx_depth)
+ return 0;
+
+ /* Find the most recent outermost entry, or a depth-zero exit. */
+ for (i = log->cnt; i > 0; i--) {
+ const struct bpf_diag_history_event *event;
+
+ event = diag_history_event(log, i - 1);
+
+ if (event->kind != BPF_DIAG_HISTORY_CONTEXT || event->ctx.kind != opts->ctx_kind)
+ continue;
+
+ if (event->ctx.enter && event->ctx.depth == 1)
+ return i - 1;
+ if (!event->ctx.enter && event->ctx.depth == 0)
+ return 0;
+ }
+
+ return 0;
+}
+
+struct bpf_diag_history_filter {
+ const struct bpf_diag_history_opts *opts;
+ u32 lineage_start;
+ bool lineage_valid;
+};
+
+static bool diag_target_matches(const struct bpf_diag_mod_target *event_target,
+ const struct bpf_diag_mod_target *target)
+{
+ int slot_off;
+
+ if (event_target->frameno != target->frameno)
+ return false;
+
+ if (event_target->kind == BPF_DIAG_MOD_TARGET_STACK_RANGE &&
+ target->kind == BPF_DIAG_MOD_TARGET_STACK_SLOT) {
+ slot_off = -(target->spi + 1) * BPF_REG_SIZE;
+ return event_target->range.min_off < slot_off + BPF_REG_SIZE &&
+ event_target->range.max_off > slot_off;
+ }
+
+ if (event_target->kind != target->kind)
+ return false;
+
+ switch (target->kind) {
+ case BPF_DIAG_MOD_TARGET_REG:
+ return event_target->regno == target->regno;
+ case BPF_DIAG_MOD_TARGET_STACK_ARG:
+ return event_target->stack_arg == target->stack_arg;
+ case BPF_DIAG_MOD_TARGET_STACK_SLOT:
+ return event_target->spi == target->spi;
+ default:
+ return false;
+ }
+}
+
+static bool diag_mod_keeps_lineage(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_event *event)
+{
+ const struct bpf_insn *insn;
+ u8 class;
+
+ if (event->mod.reason != BPF_DIAG_MOD_WRITE ||
+ event->mod.target.kind != BPF_DIAG_MOD_TARGET_REG)
+ return false;
+
+ insn = &env->prog->insnsi[event->insn_idx];
+ class = BPF_CLASS(insn->code);
+ if (class != BPF_ALU && class != BPF_ALU64)
+ return false;
+
+ switch (BPF_OP(insn->code)) {
+ case BPF_ADD:
+ case BPF_SUB:
+ case BPF_MUL:
+ case BPF_OR:
+ case BPF_AND:
+ case BPF_LSH:
+ case BPF_RSH:
+ case BPF_ARSH:
+ case BPF_XOR:
+ case BPF_NEG:
+ case BPF_END:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static void diag_build_lineage(struct bpf_verifier_env *env, struct bpf_diag_log *log,
+ struct bpf_diag_history_filter *filter)
+{
+ const struct bpf_diag_history_opts *opts = filter->opts;
+ struct bpf_diag_mod_target target;
+ int i;
+
+ for (i = 0; i < log->cnt; i++)
+ log->events[i].in_lineage = false;
+
+ if (!opts)
+ return;
+
+ if (opts->scope == BPF_DIAG_HISTORY_SCOPE_REG)
+ target = bpf_diag_reg_target(opts->frameno, opts->regno);
+ else if (opts->scope == BPF_DIAG_HISTORY_SCOPE_STACK_ARG)
+ target = bpf_diag_stack_arg_target(opts->frameno, opts->stack_arg_slot);
+ else
+ return;
+
+ /*
+ * Find the nearest mutation of the active target. A fill or spill changes
+ * the target to its origin, so the same walk follows register/stack
+ * lineage recursively until it reaches the write that created the value.
+ */
+ for (i = log->cnt; i > 0; i--) {
+ struct bpf_diag_history_event *event;
+
+ event = &log->events[i - 1];
+ if (event->kind != BPF_DIAG_HISTORY_MOD ||
+ !diag_target_matches(&event->mod.target, &target))
+ continue;
+
+ event->in_lineage = true;
+ filter->lineage_start = i - 1;
+ filter->lineage_valid = true;
+
+ if (event->mod.origin_valid) {
+ target = event->mod.origin;
+ continue;
+ }
+ if (event->mod.reason != BPF_DIAG_MOD_WRITE &&
+ event->mod.reason != BPF_DIAG_MOD_SPILL)
+ continue;
+ if (diag_mod_keeps_lineage(env, event))
+ continue;
+ break;
+ }
+
+}
+
+static int diag_history_start_idx(const struct bpf_diag_log *log,
+ const struct bpf_diag_history_filter *filter)
+{
+ const struct bpf_diag_history_opts *opts = filter->opts;
+ int i;
+
+ if (!opts || opts->scope == BPF_DIAG_HISTORY_SCOPE_ALL)
+ return 0;
+ if (opts->scope == BPF_DIAG_HISTORY_SCOPE_CONTEXT)
+ return diag_history_context_start_idx(log, opts);
+ if (filter->lineage_valid)
+ return filter->lineage_start;
+ if (opts->scope != BPF_DIAG_HISTORY_SCOPE_REF)
+ return 0;
+
+ for (i = log->cnt; i > 0; i--) {
+ const struct bpf_diag_history_event *event;
+
+ event = diag_history_event(log, i - 1);
+ if (event->kind == BPF_DIAG_HISTORY_REF_ACQUIRE &&
+ event->ref.ref_id == opts->ref_id)
+ return i - 1;
+ }
+
+ return 0;
+}
+
+static bool diag_history_event_visible(const struct bpf_diag_history_event *event,
+ const struct bpf_diag_history_filter *filter)
+{
+ const struct bpf_diag_history_opts *opts = filter->opts;
+
+ if (!opts || opts->scope == BPF_DIAG_HISTORY_SCOPE_ALL)
+ return event->kind != BPF_DIAG_HISTORY_CONTEXT;
+
+ switch (event->kind) {
+ case BPF_DIAG_HISTORY_BRANCH:
+ return true;
+ case BPF_DIAG_HISTORY_MOD:
+ return filter->lineage_valid && event->in_lineage;
+ case BPF_DIAG_HISTORY_REF_ACQUIRE:
+ case BPF_DIAG_HISTORY_REF_RELEASE:
+ return opts->scope == BPF_DIAG_HISTORY_SCOPE_REF &&
+ event->ref.ref_id == opts->ref_id;
+ case BPF_DIAG_HISTORY_CONTEXT:
+ return opts->scope == BPF_DIAG_HISTORY_SCOPE_CONTEXT &&
+ event->ctx.kind == opts->ctx_kind;
+ default:
+ return false;
+ }
+}
+
+static const char *diag_s64_bound_name(s64 value)
+{
+ if (value == S64_MIN)
+ return "S64_MIN";
+ if (value == S64_MAX)
+ return "S64_MAX";
+ return NULL;
+}
+
+static const char *diag_u64_bound_name(u64 value)
+{
+ if (value == U64_MAX)
+ return "U64_MAX";
+ return NULL;
+}
+
+static const char *diag_s64_str(struct bpf_verifier_env *env, s64 value)
+{
+ return diag_s64_bound_name(value) ?: bpf_diag_fmt(env, "%lld", value);
+}
+
+static const char *diag_u64_str(struct bpf_verifier_env *env, u64 value)
+{
+ return diag_u64_bound_name(value) ?: bpf_diag_fmt(env, "%llu", value);
+}
+
+static bool diag_range_unknown(s64 smin, s64 smax, u64 umin, u64 umax)
+{
+ return smin == S64_MIN && smax == S64_MAX && umin == 0 && umax == U64_MAX;
+}
+
+static bool diag_cnum64_unknown(struct cnum64 range)
+{
+ return diag_range_unknown(cnum64_smin(range), cnum64_smax(range), cnum64_umin(range),
+ cnum64_umax(range));
+}
+
+static bool diag_snapshot_unknown(const struct bpf_diag_reg_snapshot *snapshot)
+{
+ return tnum_is_unknown(snapshot->var_off) && diag_cnum64_unknown(snapshot->r64);
+}
+
+static const char *diag_scalar_range(struct bpf_verifier_env *env, struct cnum64 range)
+{
+ return bpf_diag_fmt(env, "signed range [%s, %s], unsigned range [%s, %s]",
+ diag_s64_str(env, cnum64_smin(range)),
+ diag_s64_str(env, cnum64_smax(range)),
+ diag_u64_str(env, cnum64_umin(range)),
+ diag_u64_str(env, cnum64_umax(range)));
+}
+
+static const char *diag_var_offset(struct bpf_verifier_env *env,
+ const struct bpf_diag_reg_snapshot *snapshot)
+{
+ if (tnum_is_const(snapshot->var_off))
+ return bpf_diag_fmt(env, "at offset %lld", (s64)snapshot->var_off.value);
+
+ if (diag_snapshot_unknown(snapshot))
+ return bpf_diag_fmt(env, "with unknown offset");
+
+ return bpf_diag_fmt(env,
+ "with variable offset: known bits %#llx, unknown mask %#llx, %s",
+ snapshot->var_off.value, snapshot->var_off.mask,
+ diag_scalar_range(env, snapshot->r64));
+}
+
+static const char *diag_snapshot_btf_type(struct bpf_verifier_env *env,
+ const struct bpf_diag_reg_snapshot *snapshot)
+{
+ if (!snapshot->btf || !snapshot->btf_id)
+ return NULL;
+
+ return bpf_diag_fmt_btf_type(env, snapshot->btf, snapshot->btf_id);
+}
+
+static const char *diag_reg_map_name(const struct bpf_map *map)
+{
+ if (!map || !map->name[0])
+ return NULL;
+
+ return map->name;
+}
+
+static const char *diag_reg_snapshot(struct bpf_verifier_env *env,
+ const struct bpf_diag_reg_snapshot *snapshot)
+{
+ const char *type_name = reg_type_str(env, snapshot->type);
+ const char *offset = diag_var_offset(env, snapshot);
+ const char *btf = diag_snapshot_btf_type(env, snapshot);
+ const char *map_name;
+
+ if (snapshot->type == SCALAR_VALUE) {
+ if (tnum_is_const(snapshot->var_off))
+ return bpf_diag_fmt(env, "integer scalar value %lld",
+ (s64)snapshot->var_off.value);
+ if (diag_snapshot_unknown(snapshot))
+ return bpf_diag_fmt(env, "integer scalar with unknown value");
+ if (cnum64_is_const(snapshot->r64))
+ return bpf_diag_fmt(env, "integer scalar value %lld",
+ cnum64_smin(snapshot->r64));
+ return bpf_diag_fmt(env, "integer scalar with %s",
+ diag_scalar_range(env, snapshot->r64));
+ }
+
+ if (snapshot->type == NOT_INIT)
+ return bpf_diag_fmt(env, "uninitialized value");
+
+ if (base_type(snapshot->type) == PTR_TO_CTX)
+ return bpf_diag_fmt(env, "context pointer %s", offset);
+
+ if (base_type(snapshot->type) == PTR_TO_STACK)
+ return bpf_diag_fmt(env, "stack pointer %s", offset);
+
+ if (base_type(snapshot->type) == PTR_TO_MAP_VALUE) {
+ const char *kind = type_may_be_null(snapshot->type) ? "nullable map value" :
+ "map value";
+
+ map_name = diag_reg_map_name(snapshot->map_ptr);
+ if (map_name)
+ return bpf_diag_fmt(env, "%s from %s %s", kind, map_name, offset);
+ return bpf_diag_fmt(env, "%s %s", kind, offset);
+ }
+
+ if (base_type(snapshot->type) == CONST_PTR_TO_MAP) {
+ map_name = diag_reg_map_name(snapshot->map_ptr);
+ if (map_name)
+ return bpf_diag_fmt(env, "map pointer for map %s", map_name);
+ return bpf_diag_fmt(env, "map pointer");
+ }
+
+ if (type_is_non_owning_ref(snapshot->type)) {
+ if (btf)
+ return bpf_diag_fmt(env, "borrowed allocated object pointer type=%s", btf);
+ return bpf_diag_fmt(env, "borrowed allocated object pointer");
+ }
+
+ if (type_is_ptr_alloc_obj(snapshot->type)) {
+ if (btf)
+ return bpf_diag_fmt(env, "owned allocated object pointer type=%s", btf);
+ return bpf_diag_fmt(env, "owned allocated object pointer");
+ }
+
+ if (base_type(snapshot->type) == PTR_TO_BTF_ID && btf)
+ return bpf_diag_fmt(env, "%s type=%s %s", type_name, btf, offset);
+
+ return bpf_diag_fmt(env, "%s %s", type_name, offset);
+}
+
+static const char *diag_mod_target_desc(struct bpf_verifier_env *env,
+ const struct bpf_diag_mod_target *target)
+{
+ switch (target->kind) {
+ case BPF_DIAG_MOD_TARGET_REG:
+ return bpf_diag_fmt(env, "R%u", target->regno);
+ case BPF_DIAG_MOD_TARGET_STACK_ARG:
+ return bpf_diag_fmt(env, "stack arg%d", diag_stack_argno(target->stack_arg));
+ case BPF_DIAG_MOD_TARGET_STACK_SLOT:
+ return bpf_diag_fmt(env, "stack slot fp%d", -(target->spi + 1) * BPF_REG_SIZE);
+ default:
+ return "value";
+ }
+}
+
+static void diag_print_mod(struct bpf_verifier_env *env, const struct bpf_diag_history_event *event)
+{
+ const struct bpf_diag_mod_target *target = &event->mod.target;
+ const char *target_desc, *reason = NULL, *old, *new;
+ const char *label = "update";
+
+ if (target->kind == BPF_DIAG_MOD_TARGET_STACK_RANGE) {
+ bpf_diag_source(
+ env, event->insn_idx, "invalidated",
+ "variable-offset stack write may affect bytes fp%d through fp%d",
+ target->range.min_off, target->range.max_off - 1);
+ return;
+ }
+
+ old = diag_reg_snapshot(env, &event->mod.old);
+ new = diag_reg_snapshot(env, &event->mod.new);
+ target_desc = diag_mod_target_desc(env, target);
+
+ switch (event->mod.reason) {
+ case BPF_DIAG_MOD_REF_RELEASE:
+ reason = target->kind == BPF_DIAG_MOD_TARGET_REG ? "resource release invalidated "
+ "this pointer" :
+ "resource release invalidated "
+ "this value";
+ break;
+ case BPF_DIAG_MOD_PKT_DATA_CHANGE:
+ reason = "packet data may have moved";
+ break;
+ case BPF_DIAG_MOD_NON_OWN_REF:
+ reason = "leaving the protected region invalidated this borrowed pointer";
+ break;
+ case BPF_DIAG_MOD_CALLER_SAVED:
+ reason = "call invalidated this caller-saved register";
+ break;
+ case BPF_DIAG_MOD_WRITE:
+ if (target->kind == BPF_DIAG_MOD_TARGET_STACK_SLOT)
+ reason = "a later stack write overwrote this spilled value";
+ break;
+ case BPF_DIAG_MOD_SPILL:
+ label = "spilled";
+ break;
+ case BPF_DIAG_MOD_VAR_WRITE:
+ default:
+ break;
+ }
+
+ if (reason) {
+ bpf_diag_source(env, event->insn_idx, "invalidated",
+ "%s: %s; previous value was %s", target_desc, reason, old);
+ return;
+ }
+
+ bpf_diag_source(env, event->insn_idx, label, "%s changed from %s to %s", target_desc,
+ old, new);
+}
+
+static void diag_print_ref_event(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_event *event)
+{
+ const char *label;
+
+ label = event->kind == BPF_DIAG_HISTORY_REF_ACQUIRE ? "acquired" : "released";
+ bpf_diag_source(env, event->insn_idx, label, "owned resource (id=%u)",
+ event->ref.ref_id);
+}
+
+static const char *diag_context_name(enum bpf_diag_context_kind kind)
+{
+ switch (kind) {
+ case BPF_DIAG_CONTEXT_RCU:
+ return "RCU read lock region";
+ case BPF_DIAG_CONTEXT_PREEMPT:
+ return "non-preemptible region";
+ case BPF_DIAG_CONTEXT_IRQ:
+ return "IRQ-disabled region";
+ case BPF_DIAG_CONTEXT_LOCK:
+ return "lock region";
+ case BPF_DIAG_CONTEXT_NONE:
+ default:
+ return "context";
+ }
+}
+
+static void diag_print_context_event(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_event *event)
+{
+ bpf_diag_source(env, event->insn_idx, "context", "%s %s; depth is now %u",
+ event->ctx.enter ? "entered" : "left",
+ diag_context_name(event->ctx.kind), event->ctx.depth);
+}
+
+static void diag_print_history(struct bpf_verifier_env *env,
+ const struct bpf_diag_history_opts *opts)
+{
+ const struct bpf_diag_history_event *event;
+ struct bpf_diag_history_filter filter = {
+ .opts = opts,
+ };
+ struct bpf_diag_log *log;
+ struct diag_fmt_mark mark;
+ bool first = true;
+ bool visible = false;
+ int start_idx;
+ u32 i;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ if (!env->diag)
+ return;
+ log = &env->diag->log;
+
+ diag_build_lineage(env, log, &filter);
+
+ start_idx = diag_history_start_idx(log, &filter);
+ for (i = start_idx; i < log->cnt; i++) {
+ event = diag_history_event(log, i);
+ if (diag_history_event_visible(event, &filter)) {
+ visible = true;
+ break;
+ }
+ }
+
+ if (!visible && !log->dropped && opts && opts->scope == BPF_DIAG_HISTORY_SCOPE_STACK_ARG)
+ return;
+
+ diag_section(env, "Causal path");
+ mark = diag_fmt_save(env);
+ for (i = start_idx; i < log->cnt; i++) {
+ event = diag_history_event(log, i);
+ if (!diag_history_event_visible(event, &filter))
+ continue;
+
+ diag_fmt_restore(env, mark);
+
+ if (!first)
+ diag_write(env, "\n");
+ first = false;
+
+ switch (event->kind) {
+ case BPF_DIAG_HISTORY_BRANCH:
+ bpf_diag_source(env, event->insn_idx, "branch",
+ "took the %s branch of this conditional, goto %s",
+ event->branch.cond_true ? "true" : "false",
+ event->branch.cond_true ? "followed" : "not followed");
+ break;
+ case BPF_DIAG_HISTORY_MOD:
+ diag_print_mod(env, event);
+ break;
+ case BPF_DIAG_HISTORY_REF_ACQUIRE:
+ case BPF_DIAG_HISTORY_REF_RELEASE:
+ diag_print_ref_event(env, event);
+ break;
+ case BPF_DIAG_HISTORY_CONTEXT:
+ diag_print_context_event(env, event);
+ break;
+ default:
+ break;
+ }
+ }
+
+ if (!visible)
+ diag_write(env, " no retained diagnostic events on this path\n");
+ if (log->dropped)
+ diag_write(env, " %u causal-history event%s not retained after diagnostic event "
+ "storage was exhausted\n",
+ log->dropped, log->dropped == 1 ? "" : "s");
+ diag_fmt_restore(env, mark);
+}
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 0cf5427a1a1b..2f243306346e 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -4,6 +4,7 @@
#ifndef __BPF_DIAGNOSTICS_H
#define __BPF_DIAGNOSTICS_H
+#include <linux/bpf.h>
#include <linux/compiler_attributes.h>
#include <linux/types.h>
@@ -90,6 +91,13 @@ enum bpf_diag_context_kind {
BPF_DIAG_CONTEXT_LOCK,
};
+enum bpf_diag_invalid_deref_kind {
+ BPF_DIAG_DEREF_SCALAR,
+ BPF_DIAG_DEREF_NULLABLE_PTR,
+ BPF_DIAG_DEREF_MODIFIED_PTR,
+ BPF_DIAG_DEREF_INVALID_PTR,
+};
+
bool bpf_diag_enabled(const struct bpf_verifier_env *env);
int bpf_diag_init(struct bpf_verifier_env *env);
char *bpf_diag_fmt_buf(struct bpf_verifier_env *env, size_t size);
@@ -97,6 +105,7 @@ const char *bpf_diag_vfmt(struct bpf_verifier_env *env, const char *fmt, va_list
__printf(2, 0);
const char *bpf_diag_fmt(struct bpf_verifier_env *env, const char *fmt, ...) __printf(2, 3);
const char *bpf_diag_fmt_btf_type(struct bpf_verifier_env *env, const struct btf *btf, u32 type_id);
+const char *bpf_diag_reg_type_plain(struct bpf_verifier_env *env, enum bpf_reg_type type);
u32 bpf_diag_event_log_pos(struct bpf_verifier_env *env);
void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos);
u32 bpf_diag_irq_depth(const struct bpf_verifier_state *state);
@@ -105,6 +114,15 @@ void bpf_diag_header(struct bpf_verifier_env *env, const char *category,
const char *problem);
void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
const char *fmt, ...) __printf(4, 5);
+void bpf_diag_register_type(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *problem, const char *reason, const char *suggestion);
+void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *reg_name, const struct bpf_reg_state *reg,
+ enum bpf_diag_invalid_deref_kind kind, s64 offset);
+void bpf_diag_unreadable_reg(struct bpf_verifier_env *env, u32 insn_idx, int regno);
+void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int nargs,
+ int stack_arg_slot, const char *callee_name,
+ const char *arg_name);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a32f360d0f00..c8b28862939f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3110,6 +3110,7 @@ static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *r
/* check whether register used as source operand can be read */
if (reg->type == NOT_INIT) {
verbose(env, "R%d !read_ok\n", regno);
+ bpf_diag_unreadable_reg(env, env->insn_idx, regno);
return -EACCES;
}
/* We don't need to worry about FP liveness because it's read-only */
@@ -4128,7 +4129,8 @@ static int mark_stack_arg_precision(struct bpf_verifier_env *env, int arg_idx)
}
static int check_outgoing_stack_args(struct bpf_verifier_env *env, struct bpf_func_state *caller,
- int nargs)
+ int nargs, const char *callee_name, const struct btf *btf,
+ const struct btf_param *args)
{
int i, spi;
@@ -4136,8 +4138,14 @@ static int check_outgoing_stack_args(struct bpf_verifier_env *env, struct bpf_fu
spi = i - MAX_BPF_FUNC_REG_ARGS;
if (spi >= caller->out_stack_arg_cnt ||
caller->stack_arg_regs[spi].type == NOT_INIT) {
+ const char *arg_name = NULL;
+
+ if (args && args[i].name_off)
+ arg_name = btf_name_by_offset(btf, args[i].name_off);
verbose(env, "callee expects %d args, stack arg%d is not initialized\n",
nargs, spi + 1);
+ bpf_diag_stack_arg_uninit(env, env->insn_idx, nargs, spi,
+ callee_name, arg_name);
return -EFAULT;
}
}
@@ -4292,6 +4300,9 @@ static int __check_ptr_off_reg(struct bpf_verifier_env *env,
if (!fixed_off_ok && reg->var_off.value != 0) {
verbose(env, "dereference of modified %s ptr %s off=%lld disallowed\n",
reg_type_str(env, reg->type), reg_arg_name(env, argno), reg->var_off.value);
+ bpf_diag_invalid_deref(env, env->insn_idx, reg_from_argno(argno),
+ reg_arg_name(env, argno), reg,
+ BPF_DIAG_DEREF_MODIFIED_PTR, reg->var_off.value);
return -EACCES;
}
@@ -6222,6 +6233,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, struct b
if (type_may_be_null(reg->type)) {
verbose(env, "%s invalid mem access '%s'\n", reg_arg_name(env, argno),
reg_type_str(env, reg->type));
+ bpf_diag_invalid_deref(env, insn_idx, reg_from_argno(argno),
+ reg_arg_name(env, argno), reg,
+ BPF_DIAG_DEREF_NULLABLE_PTR, 0);
return -EACCES;
}
@@ -6372,8 +6386,16 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, struct b
if (t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else {
+ enum bpf_diag_invalid_deref_kind kind = BPF_DIAG_DEREF_INVALID_PTR;
+
verbose(env, "%s invalid mem access '%s'\n", reg_arg_name(env, argno),
reg_type_str(env, reg->type));
+ if (reg->type == SCALAR_VALUE)
+ kind = BPF_DIAG_DEREF_SCALAR;
+ else if (type_may_be_null(reg->type))
+ kind = BPF_DIAG_DEREF_NULLABLE_PTR;
+ bpf_diag_invalid_deref(env, insn_idx, reg_from_argno(argno),
+ reg_arg_name(env, argno), reg, kind, 0);
return -EACCES;
}
@@ -9253,20 +9275,28 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
struct bpf_func_state *caller = cur_func(env);
struct bpf_verifier_log *log = &env->log;
struct ref_obj_desc ref_obj = {};
+ const struct btf_param *args;
+ const struct btf_type *func, *func_proto;
u32 i;
int ret, err;
ret = btf_prepare_func_args(env, subprog);
if (ret) {
if (bpf_in_stack_arg_cnt(sub) > 0) {
- err = check_outgoing_stack_args(env, caller, sub->arg_cnt);
+ err = check_outgoing_stack_args(env, caller, sub->arg_cnt,
+ bpf_subprog_name(env, subprog),
+ NULL, NULL);
if (err)
return err;
}
return ret;
}
- ret = check_outgoing_stack_args(env, caller, sub->arg_cnt);
+ func = btf_type_by_id(btf, env->prog->aux->func_info[subprog].type_id);
+ func_proto = btf_type_by_id(btf, func->type);
+ args = btf_params(func_proto);
+ ret = check_outgoing_stack_args(env, caller, sub->arg_cnt,
+ bpf_subprog_name(env, subprog), btf, args);
if (ret)
return ret;
@@ -12104,7 +12134,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
args = (const struct btf_param *)(meta->func_proto + 1);
nargs = btf_type_vlen(meta->func_proto);
- ret = check_outgoing_stack_args(env, caller, nargs);
+ ret = check_outgoing_stack_args(env, caller, nargs, func_name, btf, args);
if (ret)
return ret;
@@ -13785,9 +13815,8 @@ static int sanitize_check_bounds(struct bpf_verifier_env *env,
* If we return -EACCES, caller may want to try again treating pointer as a
* scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
*/
-static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
- struct bpf_insn *insn,
- const struct bpf_reg_state *ptr_reg,
+static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn,
+ u32 ptr_regno, const struct bpf_reg_state *ptr_reg,
const struct bpf_reg_state *off_reg)
{
struct bpf_verifier_state *vstate = env->cur_state;
@@ -13799,6 +13828,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
struct bpf_sanitize_info info = {};
u8 opcode = BPF_OP(insn->code);
u32 dst = insn->dst_reg;
+ const char *reason;
int ret, bounds_ret;
dst_reg = ®s[dst];
@@ -13822,12 +13852,24 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
verbose(env,
"R%d 32-bit pointer arithmetic prohibited\n",
dst);
+ reason = bpf_diag_fmt(
+ env, "R%d holds %s. 32-bit ALU operations on pointers discard pointer tracking, so the verifier cannot keep the result as a safe pointer.",
+ ptr_regno, bpf_diag_reg_type_plain(env, ptr_reg->type));
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "32-bit pointer arithmetic", reason,
+ "Use a 64-bit ALU instruction with an allowed, bounded scalar offset.");
return -EACCES;
}
if (ptr_reg->type & PTR_MAYBE_NULL) {
verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
dst, reg_type_str(env, ptr_reg->type));
+ reason = bpf_diag_fmt(
+ env, "R%d may be NULL (%s). Pointer arithmetic is allowed only after the program proves the pointer is non-NULL on this path.",
+ ptr_regno, reg_type_str(env, ptr_reg->type));
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer arithmetic before NULL check", reason,
+ "Make sure that a NULL check precedes any arithmetic performed on the pointer.");
return -EACCES;
}
@@ -13857,6 +13899,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
default:
verbose(env, "R%d pointer arithmetic on %s prohibited\n",
dst, reg_type_str(env, ptr_reg->type));
+ reason = bpf_diag_fmt(
+ env, "R%d holds %s. This pointer kind does not allow offset arithmetic.",
+ ptr_regno, bpf_diag_reg_type_plain(env, ptr_reg->type));
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer arithmetic is not allowed", reason,
+ "Do not change this pointer's offset; use it only in operations accepted for its kind.");
return -EACCES;
}
@@ -13874,9 +13922,25 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
if (base_type(ptr_reg->type) == PTR_TO_MEM && (ptr_reg->type & PTR_UNTRUSTED))
return 0;
- if (!check_reg_sane_offset_scalar(env, off_reg, ptr_reg->type) ||
- !check_reg_sane_offset_ptr(env, ptr_reg, ptr_reg->type))
+ if (!check_reg_sane_offset_scalar(env, off_reg, ptr_reg->type)) {
+ reason = bpf_diag_fmt(
+ env, "The scalar offset used with R%d is unbounded or outside the verifier's safe pointer-offset range [-%u, %u].",
+ ptr_regno, BPF_MAX_VAR_OFF, BPF_MAX_VAR_OFF);
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer offset is not safe", reason,
+ "Clamp or bounds-check the scalar offset before applying it to the pointer.");
return -EINVAL;
+ }
+ if (!check_reg_sane_offset_ptr(env, ptr_reg, ptr_reg->type)) {
+ reason = bpf_diag_fmt(
+ env, "R%d already has an offset outside the verifier's safe range [-%u, %u] for %s.",
+ ptr_regno, BPF_MAX_VAR_OFF, BPF_MAX_VAR_OFF,
+ bpf_diag_reg_type_plain(env, ptr_reg->type));
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer offset is not safe", reason,
+ "Keep the base pointer within the verifier's allowed offset range before applying more arithmetic.");
+ return -EINVAL;
+ }
/* pointer types do not carry 32-bit bounds at the moment. */
__mark_reg32_unbounded(dst_reg);
@@ -13919,6 +13983,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
/* scalar -= pointer. Creates an unknown scalar */
verbose(env, "R%d tried to subtract pointer from scalar\n",
dst);
+ reason = bpf_diag_fmt(
+ env, "This operation subtracts pointer register R%d from scalar register R%d. "
+ "The verifier only tracks pointer-minus-scalar arithmetic for allowed pointer types.",
+ ptr_regno, dst);
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer subtracted from scalar", reason,
+ "Keep the pointer as the base; only add or subtract bounded scalars when permitted.");
return -EACCES;
}
/* We don't allow subtraction from FP, because (according to
@@ -13928,6 +13999,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
if (ptr_reg->type == PTR_TO_STACK) {
verbose(env, "R%d subtraction from stack pointer prohibited\n",
dst);
+ reason = bpf_diag_fmt(
+ env, "R%d is a stack pointer. The verifier does not allow BPF_SUB to move stack pointers.",
+ ptr_regno);
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "subtraction from stack pointer", reason,
+ "Use addition from R10 to form stack addresses within the tracked stack frame.");
return -EACCES;
}
dst_reg->r64 = cnum64_add(ptr_reg->r64, cnum64_negate(off_reg->r64));
@@ -13953,16 +14030,38 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
/* bitwise ops on pointers are troublesome, prohibit. */
verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
dst, bpf_alu_string[opcode >> 4]);
+ reason = bpf_diag_fmt(
+ env, "R%d holds %s. Bitwise operator %s would destroy the pointer value the verifier is tracking.",
+ ptr_regno, bpf_diag_reg_type_plain(env, ptr_reg->type),
+ bpf_alu_string[opcode >> 4]);
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "bitwise operation on pointer", reason,
+ "Do bitwise operations on scalar values, not on pointer-valued registers.");
return -EACCES;
default:
/* other operators (e.g. MUL,LSH) produce non-pointer results */
verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
dst, bpf_alu_string[opcode >> 4]);
+ reason = bpf_diag_fmt(
+ env, "R%d holds %s. Operator %s is not one of the limited pointer arithmetic operations the verifier can track.",
+ ptr_regno, bpf_diag_reg_type_plain(env, ptr_reg->type),
+ bpf_alu_string[opcode >> 4]);
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "invalid pointer arithmetic operator", reason,
+ "Use only verifier-supported addition or subtraction with a bounded scalar offset, or perform this operation on a scalar value.");
return -EACCES;
}
- if (!check_reg_sane_offset_ptr(env, dst_reg, ptr_reg->type))
+ if (!check_reg_sane_offset_ptr(env, dst_reg, ptr_reg->type)) {
+ reason = bpf_diag_fmt(
+ env, "After this arithmetic, R%d would be outside the verifier's safe offset range [-%u, %u] for %s.",
+ dst, BPF_MAX_VAR_OFF, BPF_MAX_VAR_OFF,
+ bpf_diag_reg_type_plain(env, ptr_reg->type));
+ bpf_diag_register_type(
+ env, env->insn_idx, ptr_regno, "pointer offset is not safe", reason,
+ "Tighten the scalar bounds before the arithmetic so the resulting pointer remains within the allowed range.");
return -EINVAL;
+ }
reg_bounds_sync(dst_reg);
bounds_ret = sanitize_check_bounds(env, insn, dst_reg);
if (bounds_ret == -EACCES)
@@ -14934,15 +15033,15 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
if (err)
return err;
off_reg = *dst_reg;
- return adjust_ptr_min_max_vals(env, insn, src_reg, &off_reg);
+ return adjust_ptr_min_max_vals(env, insn, insn->src_reg, src_reg,
+ &off_reg);
}
} else if (ptr_reg) {
/* pointer += scalar */
err = mark_chain_precision(env, insn->src_reg);
if (err)
return err;
- return adjust_ptr_min_max_vals(env, insn,
- dst_reg, src_reg);
+ return adjust_ptr_min_max_vals(env, insn, insn->dst_reg, dst_reg, src_reg);
} else if (dst_reg->precise) {
/* if dst_reg is precise, src_reg should be precise as well */
err = mark_chain_precision(env, insn->src_reg);
@@ -14957,8 +15056,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
__mark_reg_known(&off_reg, insn->imm);
src_reg = &off_reg;
if (ptr_reg) /* pointer += K */
- return adjust_ptr_min_max_vals(env, insn,
- ptr_reg, src_reg);
+ return adjust_ptr_min_max_vals(env, insn, insn->dst_reg, ptr_reg, src_reg);
}
/* Got here implies adding two SCALAR_VALUEs */
diff --git a/tools/testing/selftests/bpf/progs/verifier_uninit.c b/tools/testing/selftests/bpf/progs/verifier_uninit.c
index 7718cd7d19ce..691018a46049 100644
--- a/tools/testing/selftests/bpf/progs/verifier_uninit.c
+++ b/tools/testing/selftests/bpf/progs/verifier_uninit.c
@@ -9,6 +9,7 @@
SEC("socket")
__description("read uninitialized register")
__failure __msg("R2 !read_ok")
+__msg("R2 has never been initialized on this path")
__failure_unpriv
__naked void read_uninitialized_register(void)
{
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 09/16] bpf: Report Memory Safety bounds errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (7 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 08/16] bpf: Report Register Type Safety errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 10/16] bpf: Report Resource Lifetime reference leaks Kumar Kartikeya Dwivedi
` (7 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Augment selected memory-range verifier failures with Memory Safety reports
while preserving the existing terse verifier messages for compatibility.
Cover stack spill corruption, uninitialized stack reads, variable stack helper
accesses, and check_mem_region_access() range-proof failures. The bounds report
spells out the required offset + access_size <= object_size proof with concrete
values and uses scoped diagnostic history for causal context.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 75 +++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.h | 6 +++
kernel/bpf/verifier.c | 85 +++++++++++++++++++++++++++++++++++-----
3 files changed, 157 insertions(+), 9 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 53529475b0ec..66b5ac451108 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -9,6 +9,7 @@
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/seq_buf.h>
+#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/stdarg.h>
#include <linux/string.h>
@@ -1105,6 +1106,18 @@ void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int n
"call.");
}
+void bpf_diag_memory(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion)
+{
+ bpf_diag_header(env, MEMORY_SAFETY, problem);
+ diag_reason(env, "%s", reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s", problem);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true)
{
struct bpf_diag_history_event event = {
@@ -1623,6 +1636,68 @@ static const char *diag_scalar_range(struct bpf_verifier_env *env, struct cnum64
diag_u64_str(env, cnum64_umax(range)));
}
+const char *bpf_diag_fmt_s64_sum(struct bpf_verifier_env *env, s64 value, int addend)
+{
+ s64 sum;
+
+ if (check_add_overflow(value, (s64)addend, &sum))
+ return bpf_diag_fmt(env, "%lld plus %d (%s)", value, addend,
+ addend < 0 ? "below S64_MIN" : "above S64_MAX");
+
+ return bpf_diag_fmt(env, "%lld", sum);
+}
+
+static const char *diag_access_offset(struct bpf_verifier_env *env, int off,
+ const struct bpf_reg_state *reg)
+{
+ if (tnum_is_const(reg->var_off))
+ return bpf_diag_fmt(env, "constant %s",
+ bpf_diag_fmt_s64_sum(env, (s64)reg->var_off.value, off));
+
+ if (tnum_is_unknown(reg->var_off) && diag_cnum64_unknown(reg->r64))
+ return bpf_diag_fmt(env, "unbounded");
+
+ if (off)
+ return bpf_diag_fmt(env,
+ "variable: known bits %#llx, unknown mask %#llx, plus fixed offset %d; %s",
+ (u64)reg->var_off.value, reg->var_off.mask, off,
+ diag_scalar_range(env, reg->r64));
+ return bpf_diag_fmt(env, "variable: known bits %#llx, unknown mask %#llx; %s",
+ (u64)reg->var_off.value, reg->var_off.mask,
+ diag_scalar_range(env, reg->r64));
+}
+
+void bpf_diag_mem_bounds(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *reg_name, const char *type_name, const char *proof,
+ int off, int size, u32 mem_size, const struct bpf_reg_state *reg)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_REG,
+ .frameno = diag_current_frameno(env),
+ .regno = regno,
+ };
+ const char *offset_desc;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ offset_desc = diag_access_offset(env, off, reg);
+
+ bpf_diag_header(env, MEMORY_SAFETY, "access outside bounds");
+ diag_reason(
+ env, "The verifier cannot prove offset + access_size <= object_size. Here, %s. %s is %s; offset is %s; access_size is %d; object_size is %u.",
+ proof, reg_name, type_name, offset_desc, size, mem_size);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "access may be outside object bounds");
+
+ if (regno >= 0)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(
+ env, "Add or adjust a bounds check that proves offset + access_size stays within the object.");
+}
+
static const char *diag_var_offset(struct bpf_verifier_env *env,
const struct bpf_diag_reg_snapshot *snapshot)
{
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 2f243306346e..51e6a527b075 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -13,6 +13,7 @@ struct bpf_verifier_env;
struct bpf_verifier_state;
struct btf;
+const char *bpf_diag_fmt_s64_sum(struct bpf_verifier_env *env, s64 value, int addend);
enum bpf_diag_mod_reason {
BPF_DIAG_MOD_WRITE,
BPF_DIAG_MOD_SPILL,
@@ -123,6 +124,11 @@ void bpf_diag_unreadable_reg(struct bpf_verifier_env *env, u32 insn_idx, int reg
void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int nargs,
int stack_arg_slot, const char *callee_name,
const char *arg_name);
+void bpf_diag_memory(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion);
+void bpf_diag_mem_bounds(struct bpf_verifier_env *env, u32 insn_idx, int regno,
+ const char *reg_name, const char *type_name, const char *proof,
+ int off, int size, u32 mem_size, const struct bpf_reg_state *reg);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c8b28862939f..080c6b893fb0 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3448,7 +3448,15 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
bpf_is_spilled_reg(&state->stack[spi]) &&
!bpf_is_spilled_scalar_reg(&state->stack[spi]) &&
size != BPF_REG_SIZE) {
+ const char *fmt = "This store writes %d bytes at stack offset %d into a stack slot that currently holds a spilled pointer. "
+ "Partial writes to spilled pointers are rejected because they can corrupt pointer metadata and leak kernel pointers.";
+ const char *reason;
+
verbose(env, "attempt to corrupt spilled pointer on stack\n");
+ reason = bpf_diag_fmt(env, fmt, size, off);
+ bpf_diag_memory(
+ env, insn_idx, "stack spill corruption", reason,
+ "Write the full 8-byte spilled pointer slot, or use a separate stack slot for scalar data before overwriting only part of it.");
return -EACCES;
}
@@ -3740,6 +3748,20 @@ static int mark_reg_stack_read(struct bpf_verifier_env *env,
return 0;
}
+static void bpf_diag_stack_read_uninit(struct bpf_verifier_env *env, int off, int i,
+ int size)
+{
+ const char *fmt = "This rejected read uses %d bytes at stack offset %d, but byte %d in that range is uninitialized on this path. "
+ "Programs loaded with CAP_PERFMON can be allowed to read uninitialized stack bytes, but this program is being rejected without that allowance.";
+ const char *reason;
+
+ reason = bpf_diag_fmt(env, fmt, size, off, i);
+ bpf_diag_memory(
+ env, env->insn_idx, "uninitialized stack read", reason,
+ "Initialize every byte in the stack range before reading it, adjust the offset and size so the read covers only initialized bytes, "
+ "or load with CAP_PERFMON if uninitialized stack reads are intended.");
+}
+
/* Read the stack at 'off' and put the results into the register indicated by
* 'dst_regno'. It handles reg filling if the addressed stack slot is a
* spilled reg.
@@ -3829,6 +3851,8 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
} else {
verbose(env, "invalid read from stack off %d+%d size %d\n",
off, i, size);
+ bpf_diag_stack_read_uninit(env, off, i,
+ size);
}
return -EACCES;
}
@@ -3887,6 +3911,7 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
} else {
verbose(env, "invalid read from stack off %d+%d size %d\n",
off, i, size);
+ bpf_diag_stack_read_uninit(env, off, i, size);
}
return -EACCES;
}
@@ -3979,11 +4004,18 @@ static int check_stack_read(struct bpf_verifier_env *env,
* check_stack_read_fixed_off).
*/
if (dst_regno < 0 && var_off) {
+ const char *fmt = "The helper would access the stack through variable offset %s plus fixed offset %d and size %d. "
+ "Helper stack memory arguments require a constant stack offset and a precise initialized range.";
+ const char *reason;
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
tn_buf, off, size);
+ reason = bpf_diag_fmt(env, fmt, tn_buf, off, size);
+ bpf_diag_memory(
+ env, env->insn_idx, "variable stack access", reason,
+ "Use a fixed stack offset for helper memory arguments, or copy the needed bytes into a fixed stack slot first.");
return -EACCES;
}
/* Variable offset is prohibited for unprivileged mode for simplicity
@@ -4222,10 +4254,13 @@ static int __check_mem_access(struct bpf_verifier_env *env, struct bpf_reg_state
}
/* check read/write into a memory region with possible variable offset */
-static int check_mem_region_access(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno,
- int off, int size, u32 mem_size,
+static int check_mem_region_access(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
+ argno_t argno, int off, int size, u32 mem_size,
bool zero_size_allowed)
{
+ const char *proof = "";
+ const char *start;
+ s64 max_start, max_end;
int err;
/* We may have adjusted the register pointing to memory region, so we
@@ -4239,19 +4274,32 @@ static int check_mem_region_access(struct bpf_verifier_env *env, struct bpf_reg_
* will have a set floor within our range.
*/
if (reg_smin(reg) < 0 &&
- (reg_smin(reg) == S64_MIN ||
- (off + reg_smin(reg) != (s64)(s32)(off + reg_smin(reg))) ||
- reg_smin(reg) + off < 0)) {
+ (reg_smin(reg) == S64_MIN || (off + reg_smin(reg) != (s64)(s32)(off + reg_smin(reg))) ||
+ reg_smin(reg) + off < 0)) {
verbose(env, "%s min value is negative, either use unsigned index or do a if (index >=0) check.\n",
reg_arg_name(env, argno));
- return -EACCES;
+ err = -EACCES;
+ if (bpf_diag_enabled(env)) {
+ start = bpf_diag_fmt_s64_sum(env, reg_smin(reg), off);
+ proof = bpf_diag_fmt(
+ env, "the minimal bound for a memory access is a negative value: %s",
+ start);
+ }
+ goto report_error;
}
+
err = __check_mem_access(env, reg, argno, reg_smin(reg) + off, size,
mem_size, zero_size_allowed);
if (err) {
verbose(env, "%s min value is outside of the allowed memory range\n",
reg_arg_name(env, argno));
- return err;
+ if (bpf_diag_enabled(env)) {
+ start = bpf_diag_fmt_s64_sum(env, reg_smin(reg), off);
+ proof = bpf_diag_fmt(
+ env, "the minimal bound for a memory access is %s and is outside of the object of size %u",
+ start, mem_size);
+ }
+ goto report_error;
}
/* If we haven't set a max value then we need to bail since we can't be
@@ -4261,17 +4309,36 @@ static int check_mem_region_access(struct bpf_verifier_env *env, struct bpf_reg_
if (reg_umax(reg) >= BPF_MAX_VAR_OFF) {
verbose(env, "%s unbounded memory access, make sure to bounds check any such access\n",
reg_arg_name(env, argno));
- return -EACCES;
+ err = -EACCES;
+ if (bpf_diag_enabled(env))
+ proof = bpf_diag_fmt(
+ env, "the maximal bound for a memory access is %llu and exceeds maximum allowed offset of %u",
+ reg_umax(reg), BPF_MAX_VAR_OFF);
+ goto report_error;
}
+
err = __check_mem_access(env, reg, argno, reg_umax(reg) + off, size,
mem_size, zero_size_allowed);
if (err) {
verbose(env, "%s max value is outside of the allowed memory range\n",
reg_arg_name(env, argno));
- return err;
+ if (bpf_diag_enabled(env)) {
+ max_start = (s64)reg_umax(reg) + off;
+ max_end = max_start + size;
+ proof = bpf_diag_fmt(
+ env, "the maximal bound for a memory access is %lld: start %lld + access_size %d, beyond object_size %u",
+ max_end, max_start, size, mem_size);
+ }
+ goto report_error;
}
return 0;
+
+report_error:
+ bpf_diag_mem_bounds(env, env->insn_idx, reg_from_argno(argno),
+ reg_arg_name(env, argno), reg_type_str(env, reg->type), proof,
+ off, size, mem_size, reg);
+ return err;
}
static int __check_ptr_off_reg(struct bpf_verifier_env *env,
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 10/16] bpf: Report Resource Lifetime reference leaks
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (8 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 09/16] bpf: Report Memory Safety bounds errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors Kumar Kartikeya Dwivedi
` (6 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Augment selected Resource Lifetime Safety failures with structured diagnostics
while preserving the existing verifier messages.
Report unreleased references from check_reference_leak() using
reference-scoped diagnostic history, and add state reports for dynptr,
iterator, lock, and IRQ-flag lifetime misuse.
IRQ restore mismatch and out-of-order diagnostics use IRQ context-scoped
history when an IRQ-disabled region is active, so retained save/restore context
is still visible after per-state history removal.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 90 +++++++++++++++++++++
kernel/bpf/diagnostics.h | 9 +++
kernel/bpf/verifier.c | 170 +++++++++++++++++++++++++++++++++------
3 files changed, 245 insertions(+), 24 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 66b5ac451108..708415e74ceb 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1698,6 +1698,96 @@ void bpf_diag_mem_bounds(struct bpf_verifier_env *env, u32 insn_idx, int regno,
env, "Add or adjust a bounds check that proves offset + access_size stays within the object.");
}
+static const char *diag_lock_name(const struct bpf_reference_state *lock)
+{
+ switch (lock->type) {
+ case REF_TYPE_LOCK:
+ return "bpf_spin_lock";
+ case REF_TYPE_RES_LOCK:
+ return "resource spin lock";
+ case REF_TYPE_RES_LOCK_IRQ:
+ return "IRQ-saving resource spin lock";
+ default:
+ return "lock";
+ }
+}
+
+static void diag_res_report(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason)
+{
+ bpf_diag_header(env, RESOURCE_LIFETIME_SAFETY, problem);
+ diag_reason(env, "%s", reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s", problem);
+}
+
+void bpf_diag_res(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion)
+{
+ diag_res_report(env, insn_idx, problem, reason);
+ diag_suggestion(env, "%s", suggestion);
+}
+
+void bpf_diag_lock(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion,
+ const struct bpf_reference_state *active_lock)
+{
+ diag_res_report(env, insn_idx, problem, reason);
+
+ if (active_lock) {
+ diag_section(env, "Active lock");
+ bpf_diag_source(env, active_lock->insn_idx, "acquired",
+ "active %s has verifier identity %d",
+ diag_lock_name(active_lock), active_lock->id);
+ }
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+void bpf_diag_irq(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion, u32 depth)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_CONTEXT,
+ .ctx_kind = BPF_DIAG_CONTEXT_IRQ,
+ .ctx_depth = depth,
+ };
+
+ bpf_diag_header(env, RESOURCE_LIFETIME_SAFETY, problem);
+ diag_reason(env, "%s", reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s", problem);
+
+ if (depth)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+void bpf_diag_leak(struct bpf_verifier_env *env, u32 ref_id, u32 alloc_insn, u32 fail_insn)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_REF,
+ .ref_id = ref_id,
+ };
+
+ bpf_diag_header(env, RESOURCE_LIFETIME_SAFETY, "unreleased resource");
+ diag_reason(
+ env, "Owned resource (id=%u) was acquired at instruction %u and still needs to be released before this exit path.",
+ ref_id, alloc_insn);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, fail_insn, "error",
+ "owned resource (id=%u) still needs release", ref_id);
+
+ diag_print_history(env, &opts);
+
+ diag_suggestion(
+ env, "Release or transfer ownership of the acquired resource on every path before the program exits.");
+}
+
static const char *diag_var_offset(struct bpf_verifier_env *env,
const struct bpf_diag_reg_snapshot *snapshot)
{
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 51e6a527b075..053655550856 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -8,6 +8,7 @@
#include <linux/compiler_attributes.h>
#include <linux/types.h>
+struct bpf_reference_state;
struct bpf_reg_state;
struct bpf_verifier_env;
struct bpf_verifier_state;
@@ -129,6 +130,14 @@ void bpf_diag_memory(struct bpf_verifier_env *env, u32 insn_idx, const char *pro
void bpf_diag_mem_bounds(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const char *type_name, const char *proof,
int off, int size, u32 mem_size, const struct bpf_reg_state *reg);
+void bpf_diag_res(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion);
+void bpf_diag_lock(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion,
+ const struct bpf_reference_state *active_lock);
+void bpf_diag_irq(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
+ const char *reason, const char *suggestion, u32 depth);
+void bpf_diag_leak(struct bpf_verifier_env *env, u32 ref_id, u32 alloc_insn, u32 fail_insn);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 080c6b893fb0..24ae3cb38f6d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -817,6 +817,10 @@ static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
if (dynptr_type_referenced(state->stack[spi].spilled_ptr.dynptr.type) &&
dynptr_ref_cnt(env, state->stack[spi].spilled_ptr.parent_id) <= 1) {
verbose(env, "cannot overwrite referenced dynptr\n");
+ bpf_diag_res(
+ env, env->insn_idx, "referenced dynptr overwrite",
+ "This stack slot contains a dynptr that owns or protects a referenced resource. Overwriting the last dynptr for that resource would lose the verifier-tracked release path.",
+ "Release or clone the dynptr so another live dynptr still tracks the referenced resource before overwriting this stack slot.");
return -EINVAL;
}
@@ -887,26 +891,29 @@ static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_re
return true;
}
-static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
- enum bpf_arg_type arg_type)
+static enum bpf_dynptr_type dynptr_reg_type(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
- struct bpf_func_state *state = bpf_func(env, reg);
- enum bpf_dynptr_type dynptr_type;
+ struct bpf_func_state *state;
int spi;
+ if (reg->type == CONST_PTR_TO_DYNPTR)
+ return reg->dynptr.type;
+
+ spi = dynptr_get_spi(env, reg);
+ if (spi < 0)
+ return BPF_DYNPTR_TYPE_INVALID;
+ state = bpf_func(env, reg);
+ return state->stack[spi].spilled_ptr.dynptr.type;
+}
+
+static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
+ enum bpf_arg_type arg_type)
+{
/* ARG_PTR_TO_DYNPTR takes any type of dynptr */
if (arg_type == ARG_PTR_TO_DYNPTR)
return true;
- dynptr_type = arg_to_dynptr_type(arg_type);
- if (reg->type == CONST_PTR_TO_DYNPTR) {
- return reg->dynptr.type == dynptr_type;
- } else {
- spi = dynptr_get_spi(env, reg);
- if (spi < 0)
- return false;
- return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
- }
+ return dynptr_reg_type(env, reg) == arg_to_dynptr_type(arg_type);
}
static void __mark_reg_known_zero(struct bpf_reg_state *reg);
@@ -1097,11 +1104,21 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
st = &slot->spilled_ptr;
if (st->irq.kfunc_class != kfunc_class) {
- const char *flag_kfunc = st->irq.kfunc_class == IRQ_NATIVE_KFUNC ? "native" : "lock";
+ const char *fmt = "This IRQ flag was saved by %s IRQ kfuncs, but the restore call "
+ "belongs to the %s IRQ kfunc family. Save and restore operations "
+ "must use the same family.";
+ const char *flag_kfunc = st->irq.kfunc_class == IRQ_NATIVE_KFUNC ? "native" :
+ "lock";
const char *used_kfunc = kfunc_class == IRQ_NATIVE_KFUNC ? "native" : "lock";
+ const char *reason;
verbose(env, "irq flag acquired by %s kfuncs cannot be restored with %s kfuncs\n",
flag_kfunc, used_kfunc);
+ reason = bpf_diag_fmt(env, fmt, flag_kfunc, used_kfunc);
+ bpf_diag_irq(env, env->insn_idx, "IRQ flag restore mismatch", reason,
+ "Restore the flag with the matching IRQ restore kfunc for the save "
+ "operation that created it.",
+ bpf_diag_irq_depth(env->cur_state));
return -EINVAL;
}
@@ -1119,6 +1136,11 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
verbose(env, "cannot restore irq state out of order, expected id=%d acquired at insn_idx=%d\n",
env->cur_state->active_irq_id, insn_idx);
+ bpf_diag_irq(env, env->insn_idx, "IRQ flag restore out of order",
+ "IRQ-disabled regions must be restored in last-in, first-out order, "
+ "but this restore does not match the currently active IRQ flag.",
+ "Restore nested IRQ flags in the reverse order they were saved.",
+ bpf_diag_irq_depth(env->cur_state));
return err;
}
@@ -7136,11 +7158,13 @@ enum {
* env->cur_state->active_locks remembers which map value element or allocated
* object got locked and clears it after bpf_spin_unlock.
*/
-static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno, int flags)
+static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno,
+ int flags)
{
bool is_lock = flags & PROCESS_SPIN_LOCK, is_res_lock = flags & PROCESS_RES_LOCK;
const char *lock_str = is_res_lock ? "bpf_res_spin" : "bpf_spin";
struct bpf_verifier_state *cur = env->cur_state;
+ struct bpf_reference_state *lock;
bool is_const = tnum_is_const(reg->var_off);
bool is_irq = flags & PROCESS_LOCK_IRQ;
u64 val = reg->var_off.value;
@@ -7190,14 +7214,25 @@ static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state
ptr = btf;
if (!is_res_lock && cur->active_locks) {
- if (find_lock_state(env->cur_state, REF_TYPE_LOCK, 0, NULL)) {
+ lock = find_lock_state(cur, REF_TYPE_LOCK, 0, NULL);
+ if (lock) {
verbose(env,
"Locking two bpf_spin_locks are not allowed\n");
+ bpf_diag_lock(
+ env, env->insn_idx, "nested spin lock",
+ "This path already holds a bpf_spin_lock. The verifier allows only one regular BPF spin lock at a time.",
+ "Unlock the current bpf_spin_lock before taking another one.", lock);
return -EINVAL;
}
} else if (is_res_lock && cur->active_locks) {
- if (find_lock_state(env->cur_state, REF_TYPE_RES_LOCK | REF_TYPE_RES_LOCK_IRQ, reg->id, ptr)) {
+ lock = find_lock_state(cur, REF_TYPE_RES_LOCK | REF_TYPE_RES_LOCK_IRQ,
+ reg->id, ptr);
+ if (lock) {
verbose(env, "Acquiring the same lock again, AA deadlock detected\n");
+ bpf_diag_lock(
+ env, env->insn_idx, "recursive resource spin lock",
+ "This path already holds the same resource spin lock. Taking it again would deadlock.",
+ "Avoid reacquiring the same resource spin lock before it is unlocked.", lock);
return -EINVAL;
}
}
@@ -7224,6 +7259,10 @@ static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state
if (!cur->active_locks) {
verbose(env, "%s_unlock without taking a lock\n", lock_str);
+ bpf_diag_res(
+ env, env->insn_idx, "unlock without lock",
+ "This unlock operation has no matching active lock on the current path.",
+ "Take the matching lock before this unlock, or remove the unmatched unlock path.");
return -EINVAL;
}
@@ -7233,16 +7272,35 @@ static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state
type = REF_TYPE_RES_LOCK;
else
type = REF_TYPE_LOCK;
- if (!find_lock_state(cur, type, reg->id, ptr)) {
+
+ lock = find_lock_state(cur, type, reg->id, ptr);
+ if (!lock) {
verbose(env, "%s_unlock of different lock\n", lock_str);
+ lock = find_lock_state(cur, REF_TYPE_LOCK_MASK, cur->active_lock_id,
+ cur->active_lock_ptr);
+ bpf_diag_lock(
+ env, env->insn_idx, "unlock of a different lock",
+ "This unlock does not match any active lock with the same tracked identity on the current path.",
+ "Unlock the same lock object that was most recently acquired.", lock);
return -EINVAL;
}
if (reg->id != cur->active_lock_id || ptr != cur->active_lock_ptr) {
verbose(env, "%s_unlock cannot be out of order\n", lock_str);
+ lock = find_lock_state(cur, REF_TYPE_LOCK_MASK, cur->active_lock_id,
+ cur->active_lock_ptr);
+ bpf_diag_lock(
+ env, env->insn_idx, "unlock out of order",
+ "Locks must be released in last-in, first-out order, but this unlock does not match the currently active lock.",
+ "Release nested locks in the reverse order they were acquired.", lock);
return -EINVAL;
}
if (release_lock_state(env, type, reg->id, ptr)) {
verbose(env, "%s_unlock of different lock\n", lock_str);
+ bpf_diag_lock(
+ env, env->insn_idx, "unlock of a different lock",
+ "The verifier could not release a lock state matching this unlock operation.",
+ "Pass the same lock object and lock kind that were used for the matching lock operation.",
+ lock);
return -EINVAL;
}
if (!in_rcu_cs(env))
@@ -7253,7 +7311,6 @@ static int process_spin_lock(struct bpf_verifier_env *env, struct bpf_reg_state
return 0;
}
-/* Check if @regno is a pointer to a specific field in a map value */
static int check_map_field_pointer(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno,
enum btf_field_type field_type,
struct bpf_map_desc *map_desc)
@@ -7395,9 +7452,17 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
int spi, err = 0;
if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
+ const char *fmt = "A dynptr argument must be a pointer to a dynptr stack slot or a verifier-provided const struct bpf_dynptr, but %s is %s.";
+ const char *reason;
+
verbose(env,
"%s expected pointer to stack or const struct bpf_dynptr\n",
reg_arg_name(env, argno));
+ reason = bpf_diag_fmt(env, fmt, reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
+ bpf_diag_res(
+ env, insn_idx, "invalid dynptr argument", reason,
+ "Pass the address of a stack dynptr object, or use a const dynptr pointer returned by the verifier-supported path.");
return -EINVAL;
}
@@ -7420,6 +7485,10 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
if (!is_dynptr_reg_valid_uninit(env, reg)) {
verbose(env, "Dynptr has to be an uninitialized dynptr\n");
+ bpf_diag_res(
+ env, insn_idx, "dynptr is already initialized",
+ "This kfunc constructs a dynptr and requires an uninitialized dynptr stack slot, but the selected slot already holds dynptr state.",
+ "Use a fresh stack dynptr slot, or release/destroy the existing dynptr before reusing the slot.");
return -EINVAL;
}
@@ -7436,21 +7505,37 @@ static int process_dynptr_func(struct bpf_verifier_env *env, struct bpf_reg_stat
/* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */
if (reg->type == CONST_PTR_TO_DYNPTR && (arg_type & OBJ_RELEASE)) {
verbose(env, "CONST_PTR_TO_DYNPTR cannot be released\n");
+ bpf_diag_res(
+ env, insn_idx, "const dynptr release",
+ "This release operation was given a const dynptr. Const dynptr values are verifier-provided views and cannot be released by the program.",
+ "Release only mutable dynptrs that the program initialized or reserved.");
return -EINVAL;
}
if (!is_dynptr_reg_valid_init(env, reg)) {
verbose(env, "Expected an initialized dynptr as %s\n",
reg_arg_name(env, argno));
+ bpf_diag_res(
+ env, insn_idx, "uninitialized dynptr use",
+ "This operation requires an initialized dynptr, but the stack slot does not currently hold a valid dynptr on this path.",
+ "Initialize the dynptr on every path before this call, and avoid overwriting or releasing it before this use.");
return -EINVAL;
}
/* Fold modifiers (in this case, OBJ_RELEASE) when checking expected type */
if (!is_dynptr_type_expected(env, reg, arg_type & ~OBJ_RELEASE)) {
- verbose(env,
- "Expected a dynptr of type %s as %s\n",
- dynptr_type_str(arg_to_dynptr_type(arg_type)),
- reg_arg_name(env, argno));
+ const char *fmt = "The dynptr is initialized with backing object type %s, but this operation expects dynptr type %s.";
+ enum bpf_dynptr_type expected_type = arg_to_dynptr_type(arg_type);
+ enum bpf_dynptr_type actual_type = dynptr_reg_type(env, reg);
+ const char *reason;
+
+ verbose(env, "Expected a dynptr of type %s as %s\n",
+ dynptr_type_str(expected_type), reg_arg_name(env, argno));
+ reason = bpf_diag_fmt(env, fmt, dynptr_type_str(actual_type),
+ dynptr_type_str(expected_type));
+ bpf_diag_res(
+ env, insn_idx, "wrong dynptr type", reason,
+ "Use a dynptr constructor that matches this operation, or call an operation that accepts the dynptr's current type.");
return -EINVAL;
}
@@ -7513,8 +7598,16 @@ static int process_iter_arg(struct bpf_verifier_env *env, struct bpf_reg_state *
int spi, err, i, nr_slots, btf_id;
if (reg->type != PTR_TO_STACK) {
+ const char *fmt = "Iterator state must live in verifier-tracked stack memory, but %s is %s.";
+ const char *reason;
+
verbose(env, "%s expected pointer to an iterator on stack\n",
reg_arg_name(env, argno));
+ reason = bpf_diag_fmt(env, fmt, reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
+ bpf_diag_res(
+ env, insn_idx, "invalid iterator argument", reason,
+ "Pass the address of a stack iterator object for iterator new, next, and destroy calls.");
return -EINVAL;
}
@@ -7528,6 +7621,10 @@ static int process_iter_arg(struct bpf_verifier_env *env, struct bpf_reg_state *
if (btf_id < 0) {
verbose(env, "expected valid iter pointer as %s\n",
reg_arg_name(env, argno));
+ bpf_diag_res(
+ env, insn_idx, "invalid iterator type",
+ "The kfunc expects a recognized iterator state pointer, but this argument does not match a valid iterator type.",
+ "Pass the exact iterator state type expected by this kfunc.");
return -EINVAL;
}
t = btf_type_by_id(meta->btf, btf_id);
@@ -7538,6 +7635,10 @@ static int process_iter_arg(struct bpf_verifier_env *env, struct bpf_reg_state *
if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) {
verbose(env, "expected uninitialized iter_%s as %s\n",
iter_type_str(meta->btf, btf_id), reg_arg_name(env, argno));
+ bpf_diag_res(
+ env, insn_idx, "iterator is already initialized",
+ "Iterator creation requires an uninitialized iterator stack object, but this stack range already contains iterator state.",
+ "Use a fresh iterator stack slot, or destroy the existing iterator before reusing the slot.");
return -EINVAL;
}
@@ -7562,9 +7663,17 @@ static int process_iter_arg(struct bpf_verifier_env *env, struct bpf_reg_state *
case -EINVAL:
verbose(env, "expected an initialized iter_%s as %s\n",
iter_type_str(meta->btf, btf_id), reg_arg_name(env, argno));
+ bpf_diag_res(
+ env, insn_idx, "uninitialized iterator use",
+ "This iterator operation requires an initialized iterator state object, but the stack range does not contain a live iterator on this path.",
+ "Call the matching iterator new kfunc on every path before calling next or destroy, and do not destroy the iterator before this use.");
return err;
case -EPROTO:
verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
+ bpf_diag_res(
+ env, insn_idx, "iterator requires RCU read lock",
+ "This iterator was created for use under RCU protection, but this path is not currently inside an RCU read lock region.",
+ "Wrap iterator use in bpf_rcu_read_lock() and bpf_rcu_read_unlock(), keeping all exit paths balanced.");
return err;
default:
return err;
@@ -9428,7 +9537,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
if (ret)
return ret;
- ret = process_dynptr_func(env, reg, argno, -1, arg->arg_type, &ref_obj, NULL);
+ ret = process_dynptr_func(env, reg, argno, env->insn_idx, arg->arg_type,
+ &ref_obj, NULL);
if (ret)
return ret;
} else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
@@ -10179,6 +10289,7 @@ static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exi
continue;
verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
state->refs[i].id, state->refs[i].insn_idx);
+ bpf_diag_leak(env, state->refs[i].id, state->refs[i].insn_idx, env->insn_idx);
refs_lingering = true;
}
return refs_lingering ? -EINVAL : 0;
@@ -11732,6 +11843,12 @@ static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *
if (!is_irq_flag_reg_valid_uninit(env, reg)) {
verbose(env, "expected uninitialized irq flag as %s\n",
reg_arg_name(env, argno));
+ bpf_diag_res(env, env->insn_idx, "IRQ flag is already initialized",
+ "Saving IRQ state requires an uninitialized stack slot for "
+ "the IRQ flag, but this slot already contains tracked IRQ "
+ "flag state.",
+ "Use a fresh stack slot for this save operation, or restore "
+ "the existing IRQ flag before reusing the slot.");
return -EINVAL;
}
@@ -11748,6 +11865,11 @@ static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *
if (err) {
verbose(env, "expected an initialized irq flag as %s\n",
reg_arg_name(env, argno));
+ bpf_diag_res(env, env->insn_idx, "uninitialized IRQ flag restore",
+ "Restoring IRQ state requires a stack slot that was "
+ "initialized by a matching IRQ save operation on this path.",
+ "Pass the same stack slot that was previously initialized by "
+ "the matching IRQ save kfunc.");
return err;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (9 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 10/16] bpf: Report Resource Lifetime reference leaks Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:58 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 12/16] bpf: Report Execution Context Safety errors Kumar Kartikeya Dwivedi
` (5 subsequent siblings)
16 siblings, 1 reply; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Augment selected helper and kfunc argument-contract failures with Call Type
Safety reports. Keep the existing terse verifier messages and add reason,
source context, causal register or stack-argument history, and targeted
suggestions.
Cover helper register-type mismatch, helper and kfunc non-NULL pointer
requirements, release-helper ownership requirements, scalar and constant kfunc
arguments, trusted and RCU pointer contracts, kfunc memory arguments,
memory/length pairs, refcounted kptrs, constant strings, and IRQ flag stack
arguments.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 63 ++++-
kernel/bpf/diagnostics.h | 4 +
kernel/bpf/verifier.c | 228 ++++++++++++++++--
.../selftests/bpf/progs/verifier_map_in_map.c | 1 +
4 files changed, 268 insertions(+), 28 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 708415e74ceb..c4022aba8e67 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -175,7 +175,6 @@ int bpf_diag_init(struct bpf_verifier_env *env)
env->diag = kzalloc_obj(struct bpf_diag, GFP_KERNEL_ACCOUNT);
if (!env->diag)
return -ENOMEM;
-
INIT_LIST_HEAD(&env->diag->fmt_chunks);
return 0;
}
@@ -927,6 +926,49 @@ static const char *diag_arg_ordinal(int argno)
}
}
+void bpf_diag_call_type(struct bpf_verifier_env *env, u32 insn_idx, int argno, int regno,
+ int stack_arg_slot, const char *call_name, const char *arg_name,
+ const char *reason, const char *suggestion)
+{
+ struct bpf_diag_history_opts opts = {
+ .frameno = diag_current_frameno(env),
+ };
+ const char *ordinal = diag_arg_ordinal(argno);
+ const char *arg_desc;
+ bool print_history = true;
+
+ if (regno >= 0) {
+ opts.scope = BPF_DIAG_HISTORY_SCOPE_REG;
+ opts.regno = regno;
+ } else if (stack_arg_slot >= 0) {
+ opts.scope = BPF_DIAG_HISTORY_SCOPE_STACK_ARG;
+ opts.stack_arg_slot = stack_arg_slot;
+ } else {
+ print_history = false;
+ }
+
+ if (ordinal && arg_name)
+ arg_desc = bpf_diag_fmt(env, "%s argument (%s)", ordinal, arg_name);
+ else if (ordinal)
+ arg_desc = bpf_diag_fmt(env, "%s argument", ordinal);
+ else if (arg_name)
+ arg_desc = bpf_diag_fmt(env, "argument %s", arg_name);
+ else
+ arg_desc = "argument";
+
+ bpf_diag_header(env, CALL_TYPE_SAFETY, "invalid call argument");
+ diag_reason(env, "The %s to %s does not satisfy the verifier contract: %s.",
+ arg_desc, call_name, reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "invalid %s for %s", arg_desc, call_name);
+
+ if (print_history)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const struct bpf_reg_state *reg,
enum bpf_diag_invalid_deref_kind kind, s64 offset)
@@ -1085,15 +1127,13 @@ void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int n
arg_buf = "";
bpf_diag_header(env, REGISTER_TYPE_SAFETY, "missing stack argument");
if (callee_name && *callee_name)
- diag_reason(env,
- "Function %s expects %d arguments, but %s is not initialized at "
- "this call.",
- callee_name, nargs, arg_buf);
+ diag_reason(
+ env, "Function %s expects %d arguments, but %s is not initialized at this call.",
+ callee_name, nargs, arg_buf);
else
- diag_reason(env,
- "The callee expects %d arguments, but %s is not initialized at "
- "this call.",
- nargs, arg_buf);
+ diag_reason(
+ env, "The callee expects %d arguments, but %s is not initialized at this call.",
+ nargs, arg_buf);
diag_section(env, "At");
bpf_diag_source(env, insn_idx, "error", "%s is not initialized", arg_buf);
@@ -1101,9 +1141,8 @@ void bpf_diag_stack_arg_uninit(struct bpf_verifier_env *env, u32 insn_idx, int n
if (stack_arg_slot >= 0)
diag_print_history(env, &opts);
- diag_suggestion(env, "Write the outgoing stack argument after any operation that "
- "may invalidate stored pointer values, and before making this "
- "call.");
+ diag_suggestion(
+ env, "Write the outgoing stack argument after any operation that may invalidate stored pointer values, and before making this call.");
}
void bpf_diag_memory(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 053655550856..9d4cdbcb1c75 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -6,6 +6,7 @@
#include <linux/bpf.h>
#include <linux/compiler_attributes.h>
+#include <linux/stdarg.h>
#include <linux/types.h>
struct bpf_reference_state;
@@ -138,6 +139,9 @@ void bpf_diag_lock(struct bpf_verifier_env *env, u32 insn_idx, const char *probl
void bpf_diag_irq(struct bpf_verifier_env *env, u32 insn_idx, const char *problem,
const char *reason, const char *suggestion, u32 depth);
void bpf_diag_leak(struct bpf_verifier_env *env, u32 ref_id, u32 alloc_insn, u32 fail_insn);
+void bpf_diag_call_type(struct bpf_verifier_env *env, u32 insn_idx, int argno, int regno,
+ int stack_arg_slot, const char *call_name, const char *arg_name,
+ const char *reason, const char *suggestion);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 24ae3cb38f6d..7e28f4d9f5c4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8093,13 +8093,73 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
[ARG_PTR_TO_DYNPTR] = &dynptr_types,
};
+static void bpf_diag_call_arg(struct bpf_verifier_env *env, u32 insn_idx, argno_t argno,
+ const char *call_name, const char *reason,
+ const char *suggestion)
+{
+ int arg = arg_from_argno(argno);
+ int stack_slot = -1;
+
+ if (arg > MAX_BPF_FUNC_REG_ARGS)
+ stack_slot = arg - MAX_BPF_FUNC_REG_ARGS - 1;
+
+ bpf_diag_call_type(env, insn_idx, arg, reg_from_argno(argno), stack_slot,
+ call_name && *call_name ? call_name : "call",
+ reg_arg_name(env, argno), reason, suggestion);
+}
+
+static const char *diag_btf_type_name(struct bpf_verifier_env *env, const struct btf *btf,
+ u32 type_id)
+{
+ return bpf_diag_fmt_btf_type(env, btf, type_id);
+}
+
+static const char *diag_arg_name(struct bpf_verifier_env *env, argno_t argno)
+{
+ return bpf_diag_fmt(env, "%s", reg_arg_name(env, argno));
+}
+
+__printf(6, 7) static void diag_call_arg_fmt(struct bpf_verifier_env *env, u32 insn_idx,
+ argno_t argno, const char *call_name,
+ const char *suggestion, const char *fmt, ...)
+{
+ const char *reason;
+ va_list args;
+
+ va_start(args, fmt);
+ reason = bpf_diag_vfmt(env, fmt, args);
+ va_end(args);
+
+ bpf_diag_call_arg(env, insn_idx, argno, call_name, reason, suggestion);
+}
+
+static const char *diag_expected_reg_types(struct bpf_verifier_env *env,
+ const enum bpf_reg_type *types, int count)
+{
+ size_t len = 0, size = 1;
+ char *buf;
+ int i;
+
+ for (i = 0; i < count; i++)
+ size += strlen(reg_type_str(env, types[i])) + (i ? 2 : 0);
+
+ buf = bpf_diag_fmt_buf(env, size);
+ if (!buf)
+ return "";
+
+ for (i = 0; i < count; i++)
+ len += scnprintf(buf + len, size - len, "%s%s", i ? ", " : "",
+ reg_type_str(env, types[i]));
+ return buf;
+}
+
static int check_reg_type(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno,
- enum bpf_arg_type arg_type,
- const u32 *arg_btf_id,
- struct bpf_call_arg_meta *meta)
+ enum bpf_arg_type arg_type, const u32 *arg_btf_id,
+ struct bpf_call_arg_meta *meta, const char *call_name)
{
enum bpf_reg_type expected, type = reg->type;
const struct bpf_reg_types *compatible;
+ const char *actual, *accepted;
int i, j, err;
compatible = compatible_reg_types[base_type(arg_type)];
@@ -8146,6 +8206,12 @@ static int check_reg_type(struct bpf_verifier_env *env, struct bpf_reg_state *re
for (j = 0; j + 1 < i; j++)
verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
+ actual = bpf_diag_fmt(env, "%s", reg_type_str(env, reg->type));
+ accepted = diag_expected_reg_types(env, compatible->types, i);
+ diag_call_arg_fmt(env, env->insn_idx, argno, call_name,
+ "Pass a value with one of the accepted pointer or scalar types for this call.",
+ "it has type %s, but this argument accepts %s",
+ actual, accepted);
return -EACCES;
found:
@@ -8182,6 +8248,10 @@ static int check_reg_type(struct bpf_verifier_env *env, struct bpf_reg_state *re
(!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) {
verbose(env, "Possibly NULL pointer passed to helper %s\n",
reg_arg_name(env, argno));
+ bpf_diag_call_arg(
+ env, env->insn_idx, argno, call_name,
+ "the pointer may be NULL, but this call requires a non-NULL pointer",
+ "Add a NULL check and make the call only on the non-NULL path.");
return -EACCES;
}
@@ -8562,7 +8632,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK)
arg_btf_id = fn->arg_btf_id[arg];
- err = check_reg_type(env, reg, argno, arg_type, arg_btf_id, meta);
+ err = check_reg_type(env, reg, argno, arg_type, arg_btf_id, meta,
+ func_id_name(meta->func_id));
if (err)
return err;
@@ -8575,6 +8646,10 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
!reg_is_referenced(env, reg) && !bpf_register_is_null(reg)) {
verbose(env, "release helper %s expects referenced PTR_TO_BTF_ID passed to %s\n",
func_id_name(meta->func_id), reg_arg_name(env, argno));
+ bpf_diag_call_arg(
+ env, insn_idx, argno, func_id_name(meta->func_id),
+ "release helpers require a value that owns a live resource returned by a matching acquire helper",
+ "Pass the resource-owning pointer returned by the matching acquire helper, and avoid calling the release helper after ownership has already been transferred or released.");
return -EINVAL;
}
@@ -9549,7 +9624,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
continue;
memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */
- err = check_reg_type(env, reg, argno, arg->arg_type, &arg->btf_id, &meta);
+ err = check_reg_type(env, reg, argno, arg->arg_type, &arg->btf_id, &meta,
+ bpf_subprog_name(env, subprog));
err = err ?: check_func_arg_reg_off(env, reg, argno, arg->arg_type);
if (err)
return err;
@@ -12361,29 +12437,43 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
t = btf_type_skip_modifiers(btf, args[i].type, NULL);
- if (btf_type_is_ptr(t) && (bpf_register_is_null(reg) || type_may_be_null(reg->type)) &&
+ if (btf_type_is_ptr(t)) {
+ ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
+ ref_tname = btf_name_by_offset(btf, ref_t->name_off);
+ }
+
+ if (btf_type_is_ptr(t) &&
+ (bpf_register_is_null(reg) || type_may_be_null(reg->type)) &&
!type_may_be_null(kf_arg_type)) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
verbose(env, "Possibly NULL pointer passed to trusted %s\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Add a NULL check and call the kfunc only on the non-NULL path.",
+ "the pointer may be NULL, but this kfunc requires a non-NULL pointer to %s",
+ expected_type);
return -EACCES;
}
if (regno == meta->release_regno && !is_kfunc_arg_dynptr(meta->btf, &args[i]) &&
!reg_is_referenced(env, reg) && !bpf_register_is_null(reg)) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
verbose(env, "release kfunc %s expects referenced PTR_TO_BTF_ID passed to %s\n",
func_name, reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass the resource-owning pointer returned by the matching acquire kfunc, and avoid calling the release kfunc after ownership has already been transferred or released.",
+ "release kfuncs require a resource-owning pointer to %s returned by a matching acquire kfunc",
+ expected_type);
return -EINVAL;
}
if (reg_is_referenced(env, reg))
update_ref_obj(&meta->ref_obj, reg);
- if (btf_type_is_ptr(t)) {
- ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
- ref_tname = btf_name_by_offset(btf, ref_t->name_off);
- }
-
-
if (bpf_register_is_null(reg) && type_may_be_null(kf_arg_type))
continue;
@@ -12443,35 +12533,67 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
case KF_ARG_CONST:
if (reg->type != SCALAR_VALUE) {
verbose(env, "%s is not a scalar\n", reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass an integer scalar value for this argument, not a pointer or resource object.",
+ "the kfunc expects an integer scalar, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
ret = process_const_arg(env, reg, argno, meta);
- if (ret < 0)
+ if (ret < 0) {
+ if (ret == -EINVAL)
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a compile-time constant or a value the verifier can prove is constant at this call.",
+ "the kfunc requires this scalar argument to be a verifier-known constant, but %s is variable on this path",
+ reg_arg_name(env, argno));
return ret;
+ }
break;
case KF_ARG_ANYTHING:
if (reg->type != SCALAR_VALUE) {
verbose(env, "%s is not a scalar\n", reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass an integer scalar value for this argument, not a pointer or resource object.",
+ "the kfunc expects an integer scalar, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
break;
case KF_ARG_CONST_ALLOC_SIZE_OR_ZERO:
if (reg->type != SCALAR_VALUE) {
verbose(env, "%s is not a scalar\n", reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass an integer scalar value for this argument, not a pointer or resource object.",
+ "the kfunc expects an integer scalar, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size"))
meta->r0_rdonly = true;
ret = process_const_alloc_mem_size(env, reg, argno, &meta->ret_mem);
- if (ret < 0)
+ if (ret < 0) {
+ if (ret == -EINVAL)
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a verifier-known constant size for this kfunc buffer argument.",
+ "the kfunc uses this argument as a return-buffer size, but %s is invalid or variable on this path",
+ reg_arg_name(env, argno));
return ret;
+ }
break;
case KF_ARG_PTR_TO_CTX:
if (reg->type != PTR_TO_CTX) {
verbose(env, "%s expected pointer to ctx, but got %s\n",
reg_arg_name(env, argno), reg_type_str(env, reg->type));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass the original program context pointer or preserve it before modifying registers.",
+ "the kfunc expects a context pointer, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
@@ -12505,10 +12627,19 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
} else {
verbose(env, "%s expected pointer to allocated object\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a pointer returned by the matching BPF object allocation path.",
+ "the kfunc expects an allocated object pointer, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
if (!reg_is_referenced(env, reg)) {
verbose(env, "allocated object must be referenced\n");
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass the owned object pointer before it is released or transferred.",
+ "the allocated object pointer in %s must still carry verifier-tracked ownership, but this pointer no longer owns a live resource",
+ reg_arg_name(env, argno));
return -EINVAL;
}
if (meta->btf == btf_vmlinux) {
@@ -12661,18 +12792,37 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (!is_trusted_reg(env, reg) ||
bpf_type_has_unsafe_modifiers(reg->type)) {
if (!is_kfunc_rcu(meta)) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
verbose(env, "%s must be referenced or trusted\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a pointer acquired from a verifier-tracked source, or call this kfunc only inside the required protection if it accepts RCU pointers.",
+ "the kfunc requires a trusted or resource-owning pointer to %s, but %s is %s",
+ expected_type,
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
if (!is_rcu_reg(reg)) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
verbose(env, "%s must be a rcu pointer\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Use this kfunc with a pointer that is valid in an RCU read lock region.",
+ "the kfunc requires an RCU-protected pointer to %s, but %s is %s",
+ expected_type,
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
}
- ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i, argno);
+ ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname,
+ ref_id, meta, i, argno);
if (ret < 0)
return ret;
break;
@@ -12680,6 +12830,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (!__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0)) {
enum bpf_reg_type reg2btf_type = lookup_reg2btf_ids(ref_id);
+ const char *expected_type;
verbose(env, "%s is %s expected %s %s",
reg_arg_name(env, argno), reg_type_str(env, reg->type),
@@ -12687,6 +12838,12 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (reg2btf_type != NOT_INIT)
verbose(env, " or %s", reg_type_str(env, reg2btf_type));
verbose(env, "\n");
+ expected_type = diag_btf_type_name(env, btf, ref_id);
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a verifier-tracked pointer to the expected kernel object type, not a pointer to stack storage or another memory buffer.",
+ "the kfunc expects a pointer to %s, but this argument is %s and cannot be used as that kernel object pointer",
+ expected_type,
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
@@ -12706,8 +12863,17 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
return -EINVAL;
}
ret = check_mem_reg(env, reg, argno, type_size, BPF_READ | BPF_WRITE, meta);
- if (ret < 0)
+ if (ret < 0) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass stack, map, context, or other verifier-known memory of the expected type and size, not an integer cast to a pointer.",
+ "the kfunc expects %u bytes of memory for %s, but it is %s and not verifier-known memory",
+ type_size, expected_type,
+ bpf_diag_reg_type_plain(env, reg->type));
return ret;
+ }
}
break;
case KF_ARG_CONST_MEM_SIZE:
@@ -12723,6 +12889,11 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (reg->type != SCALAR_VALUE) {
verbose(env, "%s is not a scalar\n", reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass an integer scalar length for this memory argument.",
+ "the kfunc expects a scalar memory size, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
@@ -12732,9 +12903,17 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
ret = check_mem_size_reg(env, buff_reg, size_reg, buff_argno, argno,
BPF_READ | BPF_WRITE, true, meta);
if (ret < 0) {
+ const char *buff_arg, *size_arg;
+
+ buff_arg = diag_arg_name(env, buff_argno);
+ size_arg = diag_arg_name(env, argno);
verbose(env, "%s and ", reg_arg_name(env, buff_argno));
verbose(env, "%s memory, len pair leads to invalid memory access\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, buff_argno, func_name,
+ "Pass a stack, map, context, or other verifier-known memory pointer, and keep the paired length within that object.",
+ "it is the memory pointer in a memory/length pair with %s, but %s does not describe verifier-readable memory for the requested length",
+ size_arg, buff_arg);
return ret;
}
break;
@@ -12748,8 +12927,15 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
break;
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
if (!type_is_ptr_alloc_obj(reg->type)) {
+ const char *expected_type;
+
+ expected_type = diag_btf_type_name(env, btf, ref_id);
verbose(env, "%s is neither owning or non-owning ref\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a pointer returned by the matching BPF object allocation or lookup operation for this kfunc.",
+ "the kfunc expects a pointer to BPF-managed refcounted object type %s, but this argument is not such an object pointer",
+ expected_type);
return -EINVAL;
}
if (!type_is_non_owning_ref(reg->type))
@@ -12774,6 +12960,11 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (reg->type != PTR_TO_MAP_VALUE) {
verbose(env, "%s doesn't point to a const string\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass a constant string pointer that the verifier recognizes, such as a string stored in a read-only map value.",
+ "the kfunc expects a pointer to a constant string stored in verifier-known memory, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
ret = check_arg_const_str(env, reg, argno);
@@ -12814,6 +13005,11 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
if (reg->type != PTR_TO_STACK) {
verbose(env, "%s doesn't point to an irq flag on stack\n",
reg_arg_name(env, argno));
+ diag_call_arg_fmt(env, insn_idx, argno, func_name,
+ "Pass the same stack slot used by bpf_local_irq_save() or bpf_res_spin_lock_irqsave().",
+ "the kfunc expects a stack pointer to an IRQ flag slot, but %s is %s",
+ reg_arg_name(env, argno),
+ bpf_diag_reg_type_plain(env, reg->type));
return -EINVAL;
}
ret = process_irq_flag(env, reg, argno, meta);
diff --git a/tools/testing/selftests/bpf/progs/verifier_map_in_map.c b/tools/testing/selftests/bpf/progs/verifier_map_in_map.c
index 7918646e5bfc..d3be69a9a755 100644
--- a/tools/testing/selftests/bpf/progs/verifier_map_in_map.c
+++ b/tools/testing/selftests/bpf/progs/verifier_map_in_map.c
@@ -155,6 +155,7 @@ l0_%=: r0 = 0; \
SEC("socket")
__description("forgot null checking on the inner map pointer")
__failure __msg("R1 type=map_ptr_or_null expected=map_ptr")
+__msg("map_ptr_or_null, but this argument accepts map_ptr")
__failure_unpriv
__naked void on_the_inner_map_pointer(void)
{
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 12/16] bpf: Report Execution Context Safety errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (10 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 13/16] bpf: Report Program Structure CFG errors Kumar Kartikeya Dwivedi
` (4 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Augment selected sleepability and critical-section failures with Execution
Context Safety reports. Keep the existing verifier messages and add source
context, path history, and suggestions tied to the active context.
Use the context history recorded earlier to anchor causal paths to lock, IRQ,
RCU, and preempt regions instead of unrelated register updates.
Cover global calls while holding a lock, sleepable global function calls,
sleepable helpers, sleepable kfunc calls from disallowed contexts, operations
that exit while a context is still active, and unmatched context exits.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 186 +++++++++++++++++++++++++++++++++++----
kernel/bpf/diagnostics.h | 12 +++
kernel/bpf/verifier.c | 130 ++++++++++++++++++++++-----
3 files changed, 288 insertions(+), 40 deletions(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index c4022aba8e67..01bcc9b6b980 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -839,6 +839,23 @@ static u32 diag_current_frameno(const struct bpf_verifier_env *env)
return env->cur_state->frame[env->cur_state->curframe]->frameno;
}
+static const char *diag_context_name(enum bpf_diag_context_kind kind)
+{
+ switch (kind) {
+ case BPF_DIAG_CONTEXT_RCU:
+ return "RCU read lock region";
+ case BPF_DIAG_CONTEXT_PREEMPT:
+ return "non-preemptible region";
+ case BPF_DIAG_CONTEXT_IRQ:
+ return "IRQ-disabled region";
+ case BPF_DIAG_CONTEXT_LOCK:
+ return "lock region";
+ case BPF_DIAG_CONTEXT_NONE:
+ default:
+ return "context";
+ }
+}
+
void bpf_diag_register_type(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *problem, const char *reason, const char *suggestion)
{
@@ -969,6 +986,158 @@ void bpf_diag_call_type(struct bpf_verifier_env *env, u32 insn_idx, int argno, i
diag_suggestion(env, "%s", suggestion);
}
+static const char *diag_context_constraint(enum bpf_diag_context_kind kind)
+{
+ switch (kind) {
+ case BPF_DIAG_CONTEXT_RCU:
+ return "RCU read-side critical sections cannot call operations that may sleep";
+ case BPF_DIAG_CONTEXT_PREEMPT:
+ return "preemption-disabled code cannot call operations that may sleep";
+ case BPF_DIAG_CONTEXT_IRQ:
+ return "IRQ-disabled code cannot call operations that may sleep";
+ case BPF_DIAG_CONTEXT_LOCK:
+ return "code holding a BPF spin lock cannot call operations that may sleep";
+ case BPF_DIAG_CONTEXT_NONE:
+ default:
+ return NULL;
+ }
+}
+
+static const char *diag_active_context(struct bpf_verifier_env *env, u32 depth,
+ const char *context)
+{
+ if (depth == 1)
+ return bpf_diag_fmt(env, "an active %s (depth 1)", context);
+ return bpf_diag_fmt(env, "%u active %ss (depth %u)", depth, context, depth);
+}
+
+static u32 diag_context_depth(struct bpf_verifier_env *env, enum bpf_diag_context_kind kind)
+{
+ switch (kind) {
+ case BPF_DIAG_CONTEXT_RCU:
+ return env->cur_state->active_rcu_locks;
+ case BPF_DIAG_CONTEXT_PREEMPT:
+ return env->cur_state->active_preempt_locks;
+ case BPF_DIAG_CONTEXT_IRQ:
+ return bpf_diag_irq_depth(env->cur_state);
+ case BPF_DIAG_CONTEXT_LOCK:
+ return env->cur_state->active_locks;
+ case BPF_DIAG_CONTEXT_NONE:
+ default:
+ return 0;
+ }
+}
+
+static void diag_ctx_forbidden(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *constraint, const char *suggestion)
+{
+ u32 depth = diag_context_depth(env, ctx_kind);
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_CONTEXT,
+ .ctx_kind = ctx_kind,
+ .ctx_depth = depth,
+ };
+
+ bpf_diag_header(env, EXECUTION_CONTEXT_SAFETY,
+ "operation is not allowed in this context");
+ if (constraint) {
+ if (depth) {
+ diag_reason(
+ env, "The operation %s cannot be used in %s because %s. This path is still inside %s.",
+ operation, context, constraint, diag_active_context(env, depth, context));
+ } else {
+ diag_reason(env, "The operation %s cannot be used in %s because %s.",
+ operation, context, constraint);
+ }
+ } else {
+ diag_reason(env, "The operation %s cannot be used in %s.", operation,
+ context);
+ }
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s is not allowed in %s", operation,
+ context);
+
+ if (ctx_kind != BPF_DIAG_CONTEXT_NONE)
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+static void diag_ctx_active(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *suggestion)
+{
+ u32 depth = diag_context_depth(env, ctx_kind);
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_CONTEXT,
+ .ctx_kind = ctx_kind,
+ .ctx_depth = depth,
+ };
+
+ bpf_diag_header(env, EXECUTION_CONTEXT_SAFETY,
+ "operation is not allowed in this context");
+ diag_reason(
+ env, "The operation %s cannot be used while this path is still inside %s. Leave the region before this operation.",
+ operation, diag_active_context(env, depth, context));
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s is not allowed before leaving %s",
+ operation, context);
+
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+static void diag_ctx_underflow(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ enum bpf_diag_context_kind ctx_kind, const char *suggestion)
+{
+ struct bpf_diag_history_opts opts = {
+ .scope = BPF_DIAG_HISTORY_SCOPE_CONTEXT,
+ .ctx_kind = ctx_kind,
+ };
+ const char *context = diag_context_name(ctx_kind);
+
+ bpf_diag_header(env, EXECUTION_CONTEXT_SAFETY, "unmatched context exit");
+ diag_reason(
+ env, "The operation %s tries to leave %s, but this path has no active %s to leave. The current depth is 0.",
+ operation, context, context);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s has no matching enter on this path",
+ operation);
+
+ diag_print_history(env, &opts);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
+void bpf_diag_ctx(struct bpf_verifier_env *env, enum bpf_diag_ctx_report report, u32 insn_idx,
+ const char *operation, enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *suggestion)
+{
+ switch (report) {
+ case BPF_DIAG_CTX_FORBIDDEN:
+ diag_ctx_forbidden(env, insn_idx, operation, ctx_kind, context,
+ diag_context_constraint(ctx_kind), suggestion);
+ return;
+ case BPF_DIAG_CTX_ACTIVE:
+ diag_ctx_active(env, insn_idx, operation, ctx_kind, context, suggestion);
+ return;
+ case BPF_DIAG_CTX_UNDERFLOW:
+ diag_ctx_underflow(env, insn_idx, operation, ctx_kind, suggestion);
+ return;
+ }
+}
+
+void bpf_diag_ctx_restricted(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *constraint, const char *suggestion)
+{
+ diag_ctx_forbidden(env, insn_idx, operation, ctx_kind, context, constraint, suggestion);
+}
void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const struct bpf_reg_state *reg,
enum bpf_diag_invalid_deref_kind kind, s64 offset)
@@ -2005,23 +2174,6 @@ static void diag_print_ref_event(struct bpf_verifier_env *env,
event->ref.ref_id);
}
-static const char *diag_context_name(enum bpf_diag_context_kind kind)
-{
- switch (kind) {
- case BPF_DIAG_CONTEXT_RCU:
- return "RCU read lock region";
- case BPF_DIAG_CONTEXT_PREEMPT:
- return "non-preemptible region";
- case BPF_DIAG_CONTEXT_IRQ:
- return "IRQ-disabled region";
- case BPF_DIAG_CONTEXT_LOCK:
- return "lock region";
- case BPF_DIAG_CONTEXT_NONE:
- default:
- return "context";
- }
-}
-
static void diag_print_context_event(struct bpf_verifier_env *env,
const struct bpf_diag_history_event *event)
{
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 9d4cdbcb1c75..9479a42d105a 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -94,6 +94,12 @@ enum bpf_diag_context_kind {
BPF_DIAG_CONTEXT_LOCK,
};
+enum bpf_diag_ctx_report {
+ BPF_DIAG_CTX_FORBIDDEN,
+ BPF_DIAG_CTX_ACTIVE,
+ BPF_DIAG_CTX_UNDERFLOW,
+};
+
enum bpf_diag_invalid_deref_kind {
BPF_DIAG_DEREF_SCALAR,
BPF_DIAG_DEREF_NULLABLE_PTR,
@@ -142,6 +148,12 @@ void bpf_diag_leak(struct bpf_verifier_env *env, u32 ref_id, u32 alloc_insn, u32
void bpf_diag_call_type(struct bpf_verifier_env *env, u32 insn_idx, int argno, int regno,
int stack_arg_slot, const char *call_name, const char *arg_name,
const char *reason, const char *suggestion);
+void bpf_diag_ctx(struct bpf_verifier_env *env, enum bpf_diag_ctx_report report, u32 insn_idx,
+ const char *operation, enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *suggestion);
+void bpf_diag_ctx_restricted(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ enum bpf_diag_context_kind ctx_kind, const char *context,
+ const char *constraint, const char *suggestion);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7e28f4d9f5c4..71893c36ecce 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -217,6 +217,8 @@ static int ref_set_non_owning(struct bpf_verifier_env *env,
static bool is_trusted_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg);
static inline bool in_sleepable_context(struct bpf_verifier_env *env);
static const char *non_sleepable_context_description(struct bpf_verifier_env *env);
+static enum bpf_diag_context_kind non_sleepable_context_kind(struct bpf_verifier_env *env);
+static const char *non_sleepable_context_diag_description(struct bpf_verifier_env *env);
static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg);
static void scalar_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg);
@@ -1104,9 +1106,7 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
st = &slot->spilled_ptr;
if (st->irq.kfunc_class != kfunc_class) {
- const char *fmt = "This IRQ flag was saved by %s IRQ kfuncs, but the restore call "
- "belongs to the %s IRQ kfunc family. Save and restore operations "
- "must use the same family.";
+ const char *fmt = "This IRQ flag was saved by %s IRQ kfuncs, but the restore call belongs to the %s IRQ kfunc family. Save and restore operations must use the same family.";
const char *flag_kfunc = st->irq.kfunc_class == IRQ_NATIVE_KFUNC ? "native" :
"lock";
const char *used_kfunc = kfunc_class == IRQ_NATIVE_KFUNC ? "native" : "lock";
@@ -1115,10 +1115,10 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
verbose(env, "irq flag acquired by %s kfuncs cannot be restored with %s kfuncs\n",
flag_kfunc, used_kfunc);
reason = bpf_diag_fmt(env, fmt, flag_kfunc, used_kfunc);
- bpf_diag_irq(env, env->insn_idx, "IRQ flag restore mismatch", reason,
- "Restore the flag with the matching IRQ restore kfunc for the save "
- "operation that created it.",
- bpf_diag_irq_depth(env->cur_state));
+ bpf_diag_irq(
+ env, env->insn_idx, "IRQ flag restore mismatch", reason,
+ "Restore the flag with the matching IRQ restore kfunc for the save operation that created it.",
+ bpf_diag_irq_depth(env->cur_state));
return -EINVAL;
}
@@ -1136,11 +1136,11 @@ static int unmark_stack_slot_irq_flag(struct bpf_verifier_env *env, struct bpf_r
verbose(env, "cannot restore irq state out of order, expected id=%d acquired at insn_idx=%d\n",
env->cur_state->active_irq_id, insn_idx);
- bpf_diag_irq(env, env->insn_idx, "IRQ flag restore out of order",
- "IRQ-disabled regions must be restored in last-in, first-out order, "
- "but this restore does not match the currently active IRQ flag.",
- "Restore nested IRQ flags in the reverse order they were saved.",
- bpf_diag_irq_depth(env->cur_state));
+ bpf_diag_irq(
+ env, env->insn_idx, "IRQ flag restore out of order",
+ "IRQ-disabled regions must be restored in last-in, first-out order, but this restore does not match the currently active IRQ flag.",
+ "Restore nested IRQ flags in the reverse order they were saved.",
+ bpf_diag_irq_depth(env->cur_state));
return err;
}
@@ -9766,17 +9766,31 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (err == -EFAULT)
return err;
if (bpf_subprog_is_global(env, subprog)) {
+ const char *context;
const char *sub_name = bpf_subprog_name(env, subprog);
+ const char *operation;
if (env->cur_state->active_locks) {
verbose(env, "global function calls are not allowed while holding a lock,\n"
"use static function instead\n");
+ operation =
+ bpf_diag_fmt(env, "global function %s()", sub_name);
+ bpf_diag_ctx_restricted(
+ env, *insn_idx, operation, BPF_DIAG_CONTEXT_LOCK, "lock region",
+ "global calls are prohibited while any lock is held",
+ "Release the lock before calling the global function, or use a static function instead.");
return -EINVAL;
}
if (env->subprog_info[subprog].might_sleep && !in_sleepable_context(env)) {
verbose(env, "sleepable global function %s() called in %s\n",
sub_name, non_sleepable_context_description(env));
+ context = non_sleepable_context_diag_description(env);
+ operation = bpf_diag_fmt(env, "sleepable global function %s()", sub_name);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_FORBIDDEN, *insn_idx, operation,
+ non_sleepable_context_kind(env), context,
+ "Move the call outside the critical section, or use a non-sleepable function.");
return -EINVAL;
}
@@ -10377,6 +10391,9 @@ static int check_resource_leak(struct bpf_verifier_env *env, bool exception_exit
if (check_lock && env->cur_state->active_locks) {
verbose(env, "%s cannot be used inside bpf_spin_lock-ed region\n", prefix);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_ACTIVE, env->insn_idx, prefix, BPF_DIAG_CONTEXT_LOCK,
+ "lock region", "Release the BPF spin lock before this operation on every path.");
return -EINVAL;
}
@@ -10388,16 +10405,26 @@ static int check_resource_leak(struct bpf_verifier_env *env, bool exception_exit
if (check_lock && env->cur_state->active_irq_id) {
verbose(env, "%s cannot be used inside bpf_local_irq_save-ed region\n", prefix);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_ACTIVE, env->insn_idx, prefix, BPF_DIAG_CONTEXT_IRQ,
+ "IRQ-disabled region", "Restore the saved IRQ state before this operation on every path.");
return -EINVAL;
}
if (check_lock && env->cur_state->active_rcu_locks) {
verbose(env, "%s cannot be used inside bpf_rcu_read_lock-ed region\n", prefix);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_ACTIVE, env->insn_idx, prefix, BPF_DIAG_CONTEXT_RCU,
+ "RCU read lock region", "Call bpf_rcu_read_unlock() before this operation on every path.");
return -EINVAL;
}
if (check_lock && env->cur_state->active_preempt_locks) {
verbose(env, "%s cannot be used inside bpf_preempt_disable-ed region\n", prefix);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_ACTIVE, env->insn_idx, prefix,
+ BPF_DIAG_CONTEXT_PREEMPT, "non-preemptible region",
+ "Call bpf_preempt_enable() before this operation on every path.");
return -EINVAL;
}
@@ -10551,6 +10578,36 @@ static const char *non_sleepable_context_description(struct bpf_verifier_env *en
return "non-sleepable prog";
}
+static enum bpf_diag_context_kind non_sleepable_context_kind(struct bpf_verifier_env *env)
+{
+ if (env->cur_state->active_rcu_locks)
+ return BPF_DIAG_CONTEXT_RCU;
+ if (env->cur_state->active_preempt_locks)
+ return BPF_DIAG_CONTEXT_PREEMPT;
+ if (env->cur_state->active_irq_id)
+ return BPF_DIAG_CONTEXT_IRQ;
+ if (env->cur_state->active_locks)
+ return BPF_DIAG_CONTEXT_LOCK;
+ return BPF_DIAG_CONTEXT_NONE;
+}
+
+static const char *non_sleepable_context_diag_description(struct bpf_verifier_env *env)
+{
+ switch (non_sleepable_context_kind(env)) {
+ case BPF_DIAG_CONTEXT_RCU:
+ return "RCU read lock region";
+ case BPF_DIAG_CONTEXT_PREEMPT:
+ return "non-preemptible region";
+ case BPF_DIAG_CONTEXT_IRQ:
+ return "IRQ-disabled region";
+ case BPF_DIAG_CONTEXT_LOCK:
+ return "lock region";
+ case BPF_DIAG_CONTEXT_NONE:
+ default:
+ return "non-sleepable program";
+ }
+}
+
static int release_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
bool convert_rcu, bool release_dynptr)
{
@@ -10579,6 +10636,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
enum bpf_type_flag ret_flag;
struct bpf_reg_state *regs;
struct bpf_call_arg_meta meta;
+ const char *operation;
int insn_idx = *insn_idx_p;
bool changes_data;
int i, err, func_id;
@@ -10626,6 +10684,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
if (fn->might_sleep && !in_sleepable_context(env)) {
verbose(env, "sleepable helper %s#%d in %s\n", func_id_name(func_id), func_id,
non_sleepable_context_description(env));
+ operation = bpf_diag_fmt(env, "sleepable helper %s#%d",
+ func_id_name(func_id), func_id);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_FORBIDDEN, insn_idx, operation,
+ non_sleepable_context_kind(env), non_sleepable_context_diag_description(env),
+ "Move the helper call outside the critical section, or use a non-sleepable helper.");
return -EINVAL;
}
@@ -11919,12 +11983,10 @@ static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *
if (!is_irq_flag_reg_valid_uninit(env, reg)) {
verbose(env, "expected uninitialized irq flag as %s\n",
reg_arg_name(env, argno));
- bpf_diag_res(env, env->insn_idx, "IRQ flag is already initialized",
- "Saving IRQ state requires an uninitialized stack slot for "
- "the IRQ flag, but this slot already contains tracked IRQ "
- "flag state.",
- "Use a fresh stack slot for this save operation, or restore "
- "the existing IRQ flag before reusing the slot.");
+ bpf_diag_res(
+ env, env->insn_idx, "IRQ flag is already initialized",
+ "Saving IRQ state requires an uninitialized stack slot for the IRQ flag, but this slot already contains tracked IRQ flag state.",
+ "Use a fresh stack slot for this save operation, or restore the existing IRQ flag before reusing the slot.");
return -EINVAL;
}
@@ -11941,11 +12003,10 @@ static int process_irq_flag(struct bpf_verifier_env *env, struct bpf_reg_state *
if (err) {
verbose(env, "expected an initialized irq flag as %s\n",
reg_arg_name(env, argno));
- bpf_diag_res(env, env->insn_idx, "uninitialized IRQ flag restore",
- "Restoring IRQ state requires a stack slot that was "
- "initialized by a matching IRQ save operation on this path.",
- "Pass the same stack slot that was previously initialized by "
- "the matching IRQ save kfunc.");
+ bpf_diag_res(
+ env, env->insn_idx, "uninitialized IRQ flag restore",
+ "Restoring IRQ state requires a stack slot that was initialized by a matching IRQ save operation on this path.",
+ "Pass the same stack slot that was previously initialized by the matching IRQ save kfunc.");
return err;
}
@@ -13450,6 +13511,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
const struct btf_type *t, *ptr_type;
struct bpf_call_arg_meta meta;
struct bpf_insn_aux_data *insn_aux;
+ const char *operation;
int err, insn_idx = *insn_idx_p;
u32 i, nargs, ptr_type_id;
struct bpf_kfunc_desc *desc;
@@ -13515,6 +13577,11 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
sleepable = bpf_is_kfunc_sleepable(&meta);
if (sleepable && !in_sleepable(env)) {
verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name);
+ operation = bpf_diag_fmt(env, "sleepable kfunc %s", func_name);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_FORBIDDEN, insn_idx, operation,
+ BPF_DIAG_CONTEXT_NONE, "non-sleepable program",
+ "Mark the program sleepable if the program type allows it, or use a non-sleepable kfunc.");
return -EACCES;
}
@@ -13585,6 +13652,10 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
} else if (rcu_unlock) {
if (env->cur_state->active_rcu_locks == 0) {
verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_UNDERFLOW, insn_idx, func_name,
+ BPF_DIAG_CONTEXT_RCU, NULL,
+ "Remove the extra bpf_rcu_read_unlock() call, or ensure this path first enters an RCU read lock region.");
return -EINVAL;
}
env->cur_state->active_rcu_locks--;
@@ -13599,6 +13670,10 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
} else if (preempt_enable) {
if (env->cur_state->active_preempt_locks == 0) {
verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_UNDERFLOW, insn_idx, func_name,
+ BPF_DIAG_CONTEXT_PREEMPT, NULL,
+ "Remove the extra bpf_preempt_enable() call, or ensure this path first disables preemption.");
return -EINVAL;
}
env->cur_state->active_preempt_locks--;
@@ -13611,6 +13686,11 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (sleepable && !in_sleepable_context(env)) {
verbose(env, "kernel func %s is sleepable within %s\n",
func_name, non_sleepable_context_description(env));
+ operation = bpf_diag_fmt(env, "sleepable kfunc %s", func_name);
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_FORBIDDEN, insn_idx, operation,
+ non_sleepable_context_kind(env), non_sleepable_context_diag_description(env),
+ "Move the kfunc call outside the critical section, or use a non-sleepable kfunc.");
return -EACCES;
}
@@ -17890,6 +17970,10 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
!kfunc_spin_allowed(env, insn->imm, insn->off))) {
verbose(env,
"function calls are not allowed while holding a lock\n");
+ bpf_diag_ctx(
+ env, BPF_DIAG_CTX_ACTIVE, env->insn_idx,
+ "function call", BPF_DIAG_CONTEXT_LOCK, "lock region",
+ "Release the BPF spin lock before making this call, or move the call outside the locked region.");
return -EINVAL;
}
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 13/16] bpf: Report Program Structure CFG errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (11 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 12/16] bpf: Report Execution Context Safety errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 14/16] bpf: Report Policy helper and kfunc errors Kumar Kartikeya Dwivedi
` (3 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Augment selected subprogram CFG validation failures with Program Structure
reports. These errors are structural rather than path-dependent, so the report
focuses on source and instruction context instead of causal history.
Cover jumps that leave the current subprogram, subprograms whose last
instruction can fall through into the next subprogram, and recursive bpf2bpf
call graph edges.
Format long jump-range reasons directly in diagnostics.c, and keep the
fallthrough suggestion aligned with the verifier check by suggesting exit or
explicit jumps.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/cfg.c | 35 +++++++++++++++++++++++++++++++++++
kernel/bpf/diagnostics.c | 19 +++++++++++++++++++
kernel/bpf/diagnostics.h | 3 +++
kernel/bpf/verifier.c | 16 ++++++++++++++++
4 files changed, 73 insertions(+)
diff --git a/kernel/bpf/cfg.c b/kernel/bpf/cfg.c
index db3416a7c904..6ce0c6153907 100644
--- a/kernel/bpf/cfg.c
+++ b/kernel/bpf/cfg.c
@@ -5,6 +5,8 @@
#include <linux/filter.h>
#include <linux/sort.h>
+#include "diagnostics.h"
+
#define verbose(env, fmt, args...) bpf_verifier_log_write(env, fmt, ##args)
/* non-recursive DFS pseudo code
@@ -113,6 +115,10 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
if (w < 0 || w >= env->prog->len) {
verbose_linfo(env, t, "%d: ", t);
verbose(env, "jump out of range from insn %d to %d\n", t, w);
+ bpf_diag_program_structure(
+ env, t, "jump out of range", "Keep branch targets inside the program.",
+ "Instruction %d jumps to instruction %d, but the program only contains instructions 0 through %d.",
+ t, w, env->prog->len - 1);
return -EINVAL;
}
@@ -136,6 +142,11 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
verbose_linfo(env, t, "%d: ", t);
verbose_linfo(env, w, "%d: ", w);
verbose(env, "back-edge from insn %d to %d\n", t, w);
+ bpf_diag_program_structure(
+ env, t, "back-edge is not allowed",
+ "Load with privileges that allow this back-edge, or rewrite the control flow so it does not branch backward.",
+ "Instruction %d branches back to instruction %d. This program is being rejected without the privilege needed for this back-edge.",
+ t, w);
return -EINVAL;
} else if (insn_state[w] == EXPLORED) {
/* forward- or cross-edge */
@@ -316,6 +327,11 @@ static struct bpf_iarray *jt_from_subprog(struct bpf_verifier_env *env,
if (!jt) {
verbose(env, "no jump tables found for subprog starting at %u\n", subprog_start);
+ bpf_diag_program_structure(
+ env, subprog_start, "missing jump table",
+ "Make sure subprograms containing gotox instructions are accompanied by jump tables referencing these subprograms.",
+ "No jump table was found for the subprogram that starts at instruction %u.",
+ subprog_start);
return ERR_PTR(-EINVAL);
}
@@ -343,6 +359,11 @@ create_jt(int t, struct bpf_verifier_env *env)
if (jt->items[i] < subprog_start || jt->items[i] >= subprog_end) {
verbose(env, "jump table for insn %d points outside of the subprog [%u,%u]\n",
t, subprog_start, subprog_end);
+ bpf_diag_program_structure(
+ env, t, "jump table target out of range",
+ "Keep every jump-table target inside the same subprogram.",
+ "The jump table for instruction %d points outside subprogram range [%u,%u).",
+ t, subprog_start, subprog_end);
kvfree(jt);
return ERR_PTR(-EINVAL);
}
@@ -374,6 +395,11 @@ static int visit_gotox_insn(int t, struct bpf_verifier_env *env)
w = jt->items[i];
if (w < 0 || w >= env->prog->len) {
verbose(env, "indirect jump out of range from insn %d to %d\n", t, w);
+ bpf_diag_program_structure(
+ env, t, "indirect jump out of range",
+ "Keep indirect jump targets inside the program.",
+ "Instruction %d can jump indirectly to instruction %d, but the program only contains instructions 0 through %d.",
+ t, w, env->prog->len - 1);
return -EINVAL;
}
@@ -624,12 +650,21 @@ int bpf_check_cfg(struct bpf_verifier_env *env)
if (insn_state[i] != EXPLORED) {
verbose(env, "unreachable insn %d\n", i);
+ bpf_diag_program_structure(
+ env, i, "unreachable instruction",
+ "Remove the unreachable instruction or add valid control flow that reaches it.",
+ "Instruction %d is not reachable from the program entry point.", i);
ret = -EINVAL;
goto err_free;
}
if (bpf_is_ldimm64(insn)) {
if (insn_state[i + 1] != 0) {
verbose(env, "jump into the middle of ldimm64 insn %d\n", i);
+ bpf_diag_program_structure(
+ env, i, "jump into ldimm64 immediate",
+ "Target the first instruction of the ldimm64 pair, or restructure the jump target.",
+ "Control flow reaches the second half of the ldimm64 instruction pair that starts at instruction %d.",
+ i);
ret = -EINVAL;
goto err_free;
}
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 01bcc9b6b980..539d9b0abae4 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1138,6 +1138,25 @@ void bpf_diag_ctx_restricted(struct bpf_verifier_env *env, u32 insn_idx, const c
{
diag_ctx_forbidden(env, insn_idx, operation, ctx_kind, context, constraint, suggestion);
}
+
+void bpf_diag_program_structure(struct bpf_verifier_env *env, u32 insn_idx,
+ const char *problem, const char *suggestion,
+ const char *reason_fmt, ...)
+{
+ va_list args;
+
+ bpf_diag_header(env, PROGRAM_STRUCTURE, problem);
+ diag_section(env, "Reason");
+
+ va_start(args, reason_fmt);
+ diag_vprint_indented(env, reason_fmt, args);
+ va_end(args);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "%s", problem);
+
+ diag_suggestion(env, "%s", suggestion);
+}
void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const struct bpf_reg_state *reg,
enum bpf_diag_invalid_deref_kind kind, s64 offset)
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 9479a42d105a..3ae2b9f37741 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -154,6 +154,9 @@ void bpf_diag_ctx(struct bpf_verifier_env *env, enum bpf_diag_ctx_report report,
void bpf_diag_ctx_restricted(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
enum bpf_diag_context_kind ctx_kind, const char *context,
const char *constraint, const char *suggestion);
+void bpf_diag_program_structure(struct bpf_verifier_env *env, u32 insn_idx,
+ const char *problem, const char *suggestion,
+ const char *reason_fmt, ...) __printf(5, 6);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 71893c36ecce..91693b4232d4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3000,6 +3000,12 @@ static int check_subprogs(struct bpf_verifier_env *env)
off = i + bpf_jmp_offset(&insn[i]) + 1;
if (off < subprog_start || off >= subprog_end) {
verbose(env, "jump out of range from insn %d to %d\n", i, off);
+ bpf_diag_program_structure(
+ env, i, "jump out of range",
+ "Keep branch targets within the same subprogram, or use an explicit subprogram call.",
+ "Instruction %d jumps to instruction %d, but subprogram %d only contains instructions %d through %d. "
+ "A branch target must stay inside the same subprogram.",
+ i, off, cur_subprog, subprog_start, subprog_end - 1);
return -EINVAL;
}
next:
@@ -3012,6 +3018,11 @@ static int check_subprogs(struct bpf_verifier_env *env)
code != (BPF_JMP32 | BPF_JA) &&
code != (BPF_JMP | BPF_JA)) {
verbose(env, "last insn is not an exit or jmp\n");
+ bpf_diag_program_structure(
+ env, i, "subprogram can fall through",
+ "End each subprogram with an exit or an explicit jump that keeps control flow inside the subprogram.",
+ "Subprogram %d reaches its last instruction %d without an exit or jump, so control could continue into the next subprogram.",
+ cur_subprog, i);
return -EINVAL;
}
subprog_start = subprog_end;
@@ -3084,6 +3095,11 @@ static int sort_subprogs_topo(struct bpf_verifier_env *env)
verbose(env, "recursive call from %s() to %s()\n",
bpf_subprog_name(env, cur),
bpf_subprog_name(env, callee));
+ bpf_diag_program_structure(
+ env, idx, "recursive subprogram call",
+ "Rewrite the recursion as an explicit bounded loop, or split the logic so subprogram calls do not form a cycle.",
+ "This bpf2bpf call would make the subprogram call graph recursive. "
+ "The verifier requires a finite, acyclic call graph so it can bound stack depth and analysis.");
ret = -EINVAL;
goto out;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 14/16] bpf: Report Policy helper and kfunc errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (12 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 13/16] bpf: Report Program Structure CFG errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 15/16] bpf: Report Verifier Limit errors Kumar Kartikeya Dwivedi
` (2 subsequent siblings)
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Eduard Zingerman, Alexei Starovoitov, Andrii Nakryiko,
Daniel Borkmann, Emil Tsalapatis, kkd, kernel-team
Augment selected helper and kfunc allowability failures with Policy reports.
These reports explain which requested operation is forbidden and why, without
adding path history for non-path-dependent policy checks.
Cover unprivileged bpf2bpf and kfunc use, helper program-type restrictions,
GPL-only helpers, helper-specific allow callbacks, kfunc allowability, and
destructive kfunc capability checks.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 13 +++++++++++++
kernel/bpf/diagnostics.h | 2 ++
kernel/bpf/verifier.c | 33 ++++++++++++++++++++++++++++++++-
3 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 539d9b0abae4..74e6f3b576ff 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1157,6 +1157,19 @@ void bpf_diag_program_structure(struct bpf_verifier_env *env, u32 insn_idx,
diag_suggestion(env, "%s", suggestion);
}
+
+void bpf_diag_policy(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ const char *reason, const char *suggestion)
+{
+ bpf_diag_header(env, POLICY, "operation is not allowed");
+ diag_reason(env, "The %s is not allowed: %s.", operation, reason);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "policy check failed for %s", operation);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const struct bpf_reg_state *reg,
enum bpf_diag_invalid_deref_kind kind, s64 offset)
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index 3ae2b9f37741..fc5f2812612c 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -157,6 +157,8 @@ void bpf_diag_ctx_restricted(struct bpf_verifier_env *env, u32 insn_idx, const c
void bpf_diag_program_structure(struct bpf_verifier_env *env, u32 insn_idx,
const char *problem, const char *suggestion,
const char *reason_fmt, ...) __printf(5, 6);
+void bpf_diag_policy(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
+ const char *reason, const char *suggestion);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 91693b4232d4..8e5319f47ccb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2904,6 +2904,10 @@ static int add_subprogs(struct bpf_verifier_env *env)
if (!env->bpf_capable) {
verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
+ bpf_diag_policy(
+ env, i, "BPF-to-BPF function call",
+ "loading or calling other BPF functions requires CAP_BPF or CAP_SYS_ADMIN",
+ "Load this program with the required capability, or avoid BPF-to-BPF function calls in unprivileged programs.");
return -EPERM;
}
@@ -2956,6 +2960,10 @@ static int add_kfuncs(struct bpf_verifier_env *env)
if (!env->bpf_capable) {
verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
+ bpf_diag_policy(
+ env, i, "kernel function call",
+ "calling kernel functions requires CAP_BPF or CAP_SYS_ADMIN",
+ "Load this program with the required capability, or avoid kernel function calls in unprivileged programs.");
return -EPERM;
}
@@ -10668,17 +10676,31 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
if (err) {
verbose(env, "program of this type cannot use helper %s#%d\n",
func_id_name(func_id), func_id);
+ operation = bpf_diag_fmt(env, "helper %s#%d", func_id_name(func_id), func_id);
+ bpf_diag_policy(
+ env, insn_idx, operation, "this program type does not allow the helper",
+ "Use a helper allowed for this program type, or move the logic to a compatible program type.");
return err;
}
/* eBPF programs must be GPL compatible to use GPL-ed functions */
if (!env->prog->gpl_compatible && fn->gpl_only) {
verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
+ operation = bpf_diag_fmt(env, "helper %s#%d", func_id_name(func_id), func_id);
+ bpf_diag_policy(
+ env, insn_idx, operation,
+ "this helper is restricted to GPL-compatible programs",
+ "Use a GPL-compatible license, or replace the helper with one that is available to non-GPL programs.");
return -EINVAL;
}
if (fn->allowed && !fn->allowed(env->prog)) {
verbose(env, "helper call is not allowed in probe\n");
+ operation = bpf_diag_fmt(env, "helper %s#%d", func_id_name(func_id), func_id);
+ bpf_diag_policy(
+ env, insn_idx, operation,
+ "the helper-specific policy callback rejected this program",
+ "Use the helper only from an allowed attach point or program configuration.");
return -EINVAL;
}
@@ -13539,8 +13561,13 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
return 0;
err = bpf_fetch_kfunc_arg_meta(env, insn->imm, insn->off, &meta);
- if (err == -EACCES && meta.func_name)
+ if (err == -EACCES && meta.func_name) {
verbose(env, "calling kernel function %s is not allowed\n", meta.func_name);
+ operation = bpf_diag_fmt(env, "kfunc %s", meta.func_name);
+ bpf_diag_policy(
+ env, insn_idx, operation, "this program cannot call the kfunc",
+ "Use a kfunc allowed for this program type and attach point, or change the program context.");
+ }
if (err)
return err;
desc_btf = meta.btf;
@@ -13587,6 +13614,10 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) {
verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n");
+ operation = bpf_diag_fmt(env, "destructive kfunc %s", meta.func_name);
+ bpf_diag_policy(
+ env, insn_idx, operation, "destructive kfuncs require CAP_SYS_BOOT",
+ "Load the program with CAP_SYS_BOOT, or avoid destructive kfuncs.");
return -EACCES;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 15/16] bpf: Report Verifier Limit errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (13 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 14/16] bpf: Report Policy helper and kfunc errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 16/16] bpf: Gate verifier diagnostics on log level Kumar Kartikeya Dwivedi
2026-08-13 1:38 ` [PATCH bpf-next v4 00/16] Redesign Verification Errors Eduard Zingerman
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Augment selected verifier limit failures with Verifier Limit reports. These
reports focus on the limit that was exceeded and the observed value or
condition, rather than causal branch history.
Cover tail-call stack constraints, per-subprogram stack depth, combined call
stack depth, static and runtime bpf2bpf call-frame depth, processed-instruction
complexity, and liveness analysis complexity.
Format reason text in diagnostics.c and allocate call-chain descriptions only
on failure paths, preserving useful call-chain context without adding large
local buffers to verifier frames.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/diagnostics.c | 25 +++++
kernel/bpf/diagnostics.h | 2 +
kernel/bpf/liveness.c | 6 ++
kernel/bpf/verifier.c | 97 ++++++++++++++++++-
.../bpf/progs/test_global_func_deep_stack.c | 1 +
5 files changed, 130 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index 74e6f3b576ff..4d214898b2b4 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -1170,6 +1170,31 @@ void bpf_diag_policy(struct bpf_verifier_env *env, u32 insn_idx, const char *ope
diag_suggestion(env, "%s", suggestion);
}
+void bpf_diag_limit(struct bpf_verifier_env *env, u32 insn_idx, const char *limit,
+ const char *suggestion, const char *reason_fmt, ...)
+{
+ const char *reason, *text;
+ va_list args;
+
+ if (!bpf_diag_enabled(env))
+ return;
+
+ bpf_diag_header(env, VERIFIER_LIMIT, "limit exceeded");
+ diag_section(env, "Reason");
+
+ va_start(args, reason_fmt);
+ reason = bpf_diag_vfmt(env, reason_fmt, args);
+ va_end(args);
+ text = bpf_diag_fmt(env, "The %s limit was exceeded: %s.", limit, reason);
+
+ diag_print_wrapped_text(env, text);
+
+ diag_section(env, "At");
+ bpf_diag_source(env, insn_idx, "error", "limit exceeded: %s", limit);
+
+ diag_suggestion(env, "%s", suggestion);
+}
+
void bpf_diag_invalid_deref(struct bpf_verifier_env *env, u32 insn_idx, int regno,
const char *reg_name, const struct bpf_reg_state *reg,
enum bpf_diag_invalid_deref_kind kind, s64 offset)
diff --git a/kernel/bpf/diagnostics.h b/kernel/bpf/diagnostics.h
index fc5f2812612c..ca9ecb03241a 100644
--- a/kernel/bpf/diagnostics.h
+++ b/kernel/bpf/diagnostics.h
@@ -159,6 +159,8 @@ void bpf_diag_program_structure(struct bpf_verifier_env *env, u32 insn_idx,
const char *reason_fmt, ...) __printf(5, 6);
void bpf_diag_policy(struct bpf_verifier_env *env, u32 insn_idx, const char *operation,
const char *reason, const char *suggestion);
+void bpf_diag_limit(struct bpf_verifier_env *env, u32 insn_idx, const char *limit,
+ const char *suggestion, const char *reason_fmt, ...) __printf(5, 6);
void bpf_diag_record_branch(struct bpf_verifier_env *env, u32 insn_idx, bool cond_true);
void bpf_diag_mod_begin(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
const struct bpf_reg_state *origin, enum bpf_diag_mod_reason reason);
diff --git a/kernel/bpf/liveness.c b/kernel/bpf/liveness.c
index 1c997aeba6fa..f39f01637ac0 100644
--- a/kernel/bpf/liveness.c
+++ b/kernel/bpf/liveness.c
@@ -8,6 +8,8 @@
#include <linux/slab.h>
#include <linux/sort.h>
+#include "diagnostics.h"
+
#define verbose(env, fmt, args...) bpf_verifier_log_write(env, fmt, ##args)
struct per_frame_masks {
@@ -1856,6 +1858,10 @@ static int analyze_subprog(struct bpf_verifier_env *env,
if (++env->liveness->subprog_calls > 10000) {
verbose(env, "liveness analysis exceeded complexity limit (%d calls)\n",
env->liveness->subprog_calls);
+ bpf_diag_limit(
+ env, start, "liveness analysis complexity",
+ "Reduce the number of distinct call paths or argument patterns reaching these subprograms.",
+ "The verifier recomputed subprogram liveness too many times while tracking stack and register reads across call paths");
return -E2BIG;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8e5319f47ccb..a14315d19866 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5252,6 +5252,38 @@ struct bpf_subprog_call_depth_info {
int frame; /* # of consecutive static call stack frames on top of stack */
};
+static const char *bpf_diag_append_subprog_chain(struct bpf_verifier_env *env,
+ const char *chain, int subprog)
+{
+ const char *prefix = chain && *chain ? " -> " : "";
+ const char *name = bpf_subprog_name(env, subprog);
+ const char *old = chain ?: "";
+
+ if (name && *name)
+ return bpf_diag_fmt(env, "%s%s%s", old, prefix, name);
+ return bpf_diag_fmt(env, "%s%ssubprogram %d", old, prefix, subprog);
+}
+
+static const char *bpf_diag_alloc_subprog_call_chain(struct bpf_verifier_env *env,
+ struct bpf_subprog_call_depth_info *dinfo,
+ int idx)
+{
+ int call_chain[MAX_CALL_FRAMES + 1];
+ int i, subprog, cnt = 0;
+ const char *chain = NULL;
+
+ for (subprog = idx; subprog >= 0 && cnt < ARRAY_SIZE(call_chain);
+ subprog = dinfo[subprog].caller)
+ call_chain[cnt++] = subprog;
+
+ if (subprog >= 0)
+ chain = "...";
+ for (i = cnt - 1; i >= 0; i--)
+ chain = bpf_diag_append_subprog_chain(env, chain, call_chain[i]);
+
+ return chain;
+}
+
/* starting from main bpf function walk all instructions of the function
* and recursively walk all callees that given function can call.
* Ignore jump and exit insns.
@@ -5294,9 +5326,17 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
* of caller's stack as shown on the example above.
*/
if (idx && subprog[idx].has_tail_call && depth >= 256) {
+ const char *chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+
verbose(env,
"tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
depth);
+ bpf_diag_limit(
+ env, subprog[idx].start, "call stack with tail calls",
+ "Reduce stack usage in caller frames, or avoid combining deep bpf2bpf calls with tail calls.",
+ "Call chain %s reaches a subprogram with tail calls after caller frames already use %d bytes; "
+ "tail-call paths are limited to 256 bytes in caller frames",
+ chain ?: "the current call chain", depth);
return -EACCES;
}
@@ -5318,8 +5358,16 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
if (subprog_depth > env->max_stack_depth)
env->max_stack_depth = subprog_depth;
if (subprog_depth > MAX_BPF_STACK) {
+ const char *chain;
+
verbose(env, "stack size of subprog %d is %d. Too large\n",
idx, subprog_depth);
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ bpf_diag_limit(
+ env, subprog[idx].start, "subprogram stack depth",
+ "Reduce stack usage in this subprogram, or move large data out of the BPF stack.",
+ "Call chain %s reaches a subprogram that uses %d bytes of stack, exceeding the %d byte limit for one BPF stack frame",
+ chain ?: "the current call chain", subprog_depth, MAX_BPF_STACK);
return -EACCES;
}
} else {
@@ -5333,13 +5381,23 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
verbose(env, "combined stack size of %d calls is %d. Too large\n",
total, depth);
+ {
+ const char *chain;
+
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ bpf_diag_limit(
+ env, subprog[idx].start, "combined call stack depth",
+ "Reduce stack usage or call depth along this call chain.",
+ "Call chain %s uses %d bytes of stack across %d nested calls, exceeding the %d byte limit",
+ chain ?: "the current call chain", depth, total, MAX_BPF_STACK);
+ }
return -EACCES;
}
}
continue_func:
subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
- int next_insn, sidx;
+ int next_insn, call_insn, sidx;
if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) {
bool err = false;
@@ -5386,6 +5444,7 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
/* push caller idx into callee's dinfo */
dinfo[sidx].caller = idx;
+ call_insn = i;
i = next_insn;
idx = sidx;
@@ -5397,8 +5456,16 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
frame = bpf_subprog_is_global(env, idx) ? 0 : frame + 1;
if (frame >= MAX_CALL_FRAMES) {
+ const char *chain;
+
verbose(env, "the call stack of %d frames is too deep !\n",
frame);
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ bpf_diag_limit(
+ env, call_insn, "bpf2bpf call frames",
+ "Reduce the number of nested bpf2bpf calls on this path.",
+ "Call chain %s reaches %d static bpf2bpf call frames, exceeding the %d frame limit",
+ chain ?: "the current call chain", frame, MAX_CALL_FRAMES);
return -E2BIG;
}
goto process_func;
@@ -9490,6 +9557,22 @@ typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
struct bpf_func_state *callee,
int insn_idx);
+static const char *bpf_diag_alloc_state_call_chain(struct bpf_verifier_env *env,
+ const struct bpf_verifier_state *state,
+ int next_subprog)
+{
+ const char *chain = NULL;
+ int i;
+
+ for (i = 0; i <= state->curframe; i++)
+ chain = bpf_diag_append_subprog_chain(env, chain, state->frame[i]->subprogno);
+
+ if (next_subprog >= 0)
+ chain = bpf_diag_append_subprog_chain(env, chain, next_subprog);
+
+ return chain;
+}
+
static int set_callee_state(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee, int insn_idx);
@@ -9502,8 +9585,16 @@ static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int calls
int err;
if (state->curframe + 1 >= MAX_CALL_FRAMES) {
+ const char *chain;
+
verbose(env, "the call stack of %d frames is too deep\n",
state->curframe + 2);
+ chain = bpf_diag_alloc_state_call_chain(env, state, subprog);
+ bpf_diag_limit(
+ env, callsite, "bpf2bpf call frames",
+ "Reduce the number of nested bpf2bpf calls on this path.",
+ "Call chain %s would create %d verifier call frames, exceeding the %d frame limit",
+ chain ?: "the current call chain", state->curframe + 2, MAX_CALL_FRAMES);
return -E2BIG;
}
@@ -18098,6 +18189,10 @@ static int do_check(struct bpf_verifier_env *env)
verbose(env,
"BPF program is too large. Processed %d insn\n",
env->insn_processed);
+ bpf_diag_limit(
+ env, env->insn_idx, "processed instruction complexity",
+ "Simplify control flow, reduce branching, or split the program into smaller pieces.",
+ "The verifier explored more instructions than the complexity limit allows");
return -E2BIG;
}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func_deep_stack.c b/tools/testing/selftests/bpf/progs/test_global_func_deep_stack.c
index 1b634b543b62..621207683ce4 100644
--- a/tools/testing/selftests/bpf/progs/test_global_func_deep_stack.c
+++ b/tools/testing/selftests/bpf/progs/test_global_func_deep_stack.c
@@ -89,6 +89,7 @@ int global_func_deep_stack_success(struct __sk_buff *skb)
*/
SEC("syscall")
__failure __msg("combined stack size of 34 calls")
+__msg("Call chain ... -> f16")
int global_func_deep_stack_fail(struct __sk_buff *skb)
{
return f32(123);
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH bpf-next v4 16/16] bpf: Gate verifier diagnostics on log level
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (14 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 15/16] bpf: Report Verifier Limit errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:33 ` Kumar Kartikeya Dwivedi
2026-08-13 1:38 ` [PATCH bpf-next v4 00/16] Redesign Verification Errors Eduard Zingerman
16 siblings, 0 replies; 22+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2026-08-12 23:33 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Eduard Zingerman, Emil Tsalapatis, kkd, kernel-team
Verifier diagnostics collect active-path history and render richer reports for
selected verifier failures. That work is useful only when the caller requests
normal verifier log output.
Do not enable diagnostic collection or report rendering for BPF_LOG_STATS-only
loads. Stats-only loads still need the verifier's summary counters, but not
the extra path history used by diagnostic reports.
Keep enablement in the verifier environment and requested log mode so async
callback verification uses the same diagnostic policy as the main verifier
pass.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/verifier.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a14315d19866..fea0b96ea5f2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5326,7 +5326,10 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
* of caller's stack as shown on the example above.
*/
if (idx && subprog[idx].has_tail_call && depth >= 256) {
- const char *chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ const char *chain = NULL;
+
+ if (bpf_diag_enabled(env))
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
verbose(env,
"tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
@@ -5358,11 +5361,12 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
if (subprog_depth > env->max_stack_depth)
env->max_stack_depth = subprog_depth;
if (subprog_depth > MAX_BPF_STACK) {
- const char *chain;
+ const char *chain = NULL;
verbose(env, "stack size of subprog %d is %d. Too large\n",
idx, subprog_depth);
- chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ if (bpf_diag_enabled(env))
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
bpf_diag_limit(
env, subprog[idx].start, "subprogram stack depth",
"Reduce stack usage in this subprogram, or move large data out of the BPF stack.",
@@ -5382,9 +5386,10 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
verbose(env, "combined stack size of %d calls is %d. Too large\n",
total, depth);
{
- const char *chain;
+ const char *chain = NULL;
- chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ if (bpf_diag_enabled(env))
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
bpf_diag_limit(
env, subprog[idx].start, "combined call stack depth",
"Reduce stack usage or call depth along this call chain.",
@@ -5456,11 +5461,12 @@ static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx,
frame = bpf_subprog_is_global(env, idx) ? 0 : frame + 1;
if (frame >= MAX_CALL_FRAMES) {
- const char *chain;
+ const char *chain = NULL;
verbose(env, "the call stack of %d frames is too deep !\n",
frame);
- chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
+ if (bpf_diag_enabled(env))
+ chain = bpf_diag_alloc_subprog_call_chain(env, dinfo, idx);
bpf_diag_limit(
env, call_insn, "bpf2bpf call frames",
"Reduce the number of nested bpf2bpf calls on this path.",
@@ -9585,11 +9591,12 @@ static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int calls
int err;
if (state->curframe + 1 >= MAX_CALL_FRAMES) {
- const char *chain;
+ const char *chain = NULL;
verbose(env, "the call stack of %d frames is too deep\n",
state->curframe + 2);
- chain = bpf_diag_alloc_state_call_chain(env, state, subprog);
+ if (bpf_diag_enabled(env))
+ chain = bpf_diag_alloc_state_call_chain(env, state, subprog);
bpf_diag_limit(
env, callsite, "bpf2bpf call frames",
"Reduce the number of nested bpf2bpf calls on this path.",
--
2.53.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers
2026-08-12 23:33 ` [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers Kumar Kartikeya Dwivedi
@ 2026-08-12 23:41 ` sashiko-bot
0 siblings, 0 replies; 22+ messages in thread
From: sashiko-bot @ 2026-08-12 23:41 UTC (permalink / raw)
To: Kumar Kartikeya Dwivedi; +Cc: bpf
Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The patch completely fails to implement the prose wrapping and reusable report sections promised in the commit message.
- [Low] Diagnostic category string macros are defined in the .c file instead of the header, making them inaccessible to callers.
--
--- Patch [1]: [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers ---
commit 2d39aa0d2b938aedc24539fb306c5c0aabb08c25
Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>
bpf: Add verifier diagnostics report helpers
This patch adds a small diagnostics renderer for verifier reports and wires it
into the BPF build. It includes helpers to emit a failure header and aims to
provide reusable report sections.
> Wrap report prose at 100 columns so Reason and Suggestion text stays
> readable without changing source or instruction gutters.
[Severity: Medium]
Is this description accurate for the current implementation? Looking at the
code for bpf_diag_header() and diag_write() added in this patch, there does
not appear to be any text wrapping logic or implementation for reusable
report sections like Reason and Suggestion. Was this logic accidentally
omitted from this patch?
> diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
> new file mode 100644
> --- /dev/null
> +++ b/kernel/bpf/diagnostics.c
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +// Copyright (c) 2026 Meta Platforms, Inc. and affiliates.
> +
> +#include <linux/bpf_verifier.h>
> +#include <linux/ctype.h>
> +#include <linux/stdarg.h>
> +
> +#include "diagnostics.h"
> +
> +#define MEMORY_SAFETY "Memory Safety"
> +#define REGISTER_TYPE_SAFETY "Register Type Safety"
> +#define CALL_TYPE_SAFETY "Call Type Safety"
> +#define RESOURCE_LIFETIME_SAFETY "Resource Lifetime Safety"
> +#define EXECUTION_CONTEXT_SAFETY "Execution Context Safety"
> +#define PROGRAM_STRUCTURE "Program Structure"
> +#define POLICY "Policy"
> +#define VERIFIER_LIMIT "Verifier Limit"
[Severity: Low]
Should these category string macros be defined in diagnostics.h instead of
here in the source file? Since they are not used within diagnostics.c and
are not exported in the header file, other files in the verifier will not be
able to use them as standardized arguments when calling bpf_diag_header().
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260812233326.3575958-1-memxor@gmail.com?part=1
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events
2026-08-12 23:33 ` [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events Kumar Kartikeya Dwivedi
@ 2026-08-12 23:53 ` sashiko-bot
0 siblings, 0 replies; 22+ messages in thread
From: sashiko-bot @ 2026-08-12 23:53 UTC (permalink / raw)
To: Kumar Kartikeya Dwivedi; +Cc: bpf
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing diagnostic event tracking for BPF_LD_IMM64 and BPF_ATOMIC (with BPF_FETCH) operations.
--
--- Patch [5]: [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events ---
commit 7db736a554444e8ded5ae93ab09a9f7f17a9c87b
Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>
bpf: Track verifier register diagnostic events
This commit introduces verifier register diagnostic events to track how a
value reached its current state. It records register modifications, stack
spills, reference invalidations, and other events in the diagnostic history.
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 2e915292265b0..ed8a239a964d9 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
[ ... ]
> @@ -6391,15 +6421,19 @@ static int check_load_mem(struct bpf_verifier_env *env, struct bpf_insn *insn,
>
> src_reg_type = regs[insn->src_reg].type;
>
> - /* Check if (src_reg + off) is readable. The state of dst_reg will be
> - * updated by this call.
> + /*
> + * check_stack_read_fixed_off() may refine the modification's origin to
> + * the source stack slot.
> */
> + bpf_diag_mod_begin(env, ®s[insn->dst_reg], NULL, BPF_DIAG_MOD_WRITE);
> err = check_mem_access(env, env->insn_idx, regs + insn->src_reg, argno_from_reg(insn->src_reg), insn->off,
> BPF_SIZE(insn->code), BPF_READ, insn->dst_reg,
> strict_alignment_once, is_ldsx);
> err = err ?: save_aux_ptr_type(env, src_reg_type,
> allow_trust_mismatch);
> err = err ?: reg_bounds_sanity_check(env, ®s[insn->dst_reg], ctx);
> + if (!err)
> + bpf_diag_mod_end(env);
>
> return err;
> }
[Severity: Medium]
Are we missing similar diagnostic event tracking for BPF_LD_IMM64 and
BPF_ATOMIC (with BPF_FETCH) operations?
For example, in check_ld_imm(), we directly modify the destination register
without calling bpf_diag_mod_begin() or bpf_diag_mod_end(), which prevents
the origin of the value from being recorded:
dst_reg = ®s[insn->dst_reg];
if (insn->src_reg == 0) {
u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
dst_reg->type = SCALAR_VALUE;
__mark_reg_known(®s[insn->dst_reg], imm);
return 0;
}
Additionally, in check_atomic_rmw(), we modify load_reg but lack diagnostic
event tracing. If stack memory is fetched, check_stack_read_fixed_off() calls
bpf_diag_mod_begin(), but bpf_diag_mod_end() is never called afterwards.
load_reg = bpf_atomic_load_reg(insn);
if (load_reg >= 0) {
/* check and record load of old value */
err = check_reg_arg(env, load_reg, DST_OP);
if (err)
return err;
}
dst_reg = cur_regs(env) + insn->dst_reg;
/* Check whether we can read the memory, with second call for fetch
* case to simulate the register fill.
*/
err = check_mem_access(env, env->insn_idx, dst_reg, argno_from_reg(insn->dst_reg), insn->off,
BPF_SIZE(insn->code), BPF_READ, -1, true, false);
if (!err && load_reg >= 0)
err = check_mem_access(env, env->insn_idx, dst_reg, argno_from_reg(insn->dst_reg),
insn->off, BPF_SIZE(insn->code),
BPF_READ, load_reg, true, false);
Does this leak the active modification state and cause the stack fetch event
to be permanently lost? Should these paths also be instrumented to track
value origins correctly?
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260812233326.3575958-1-memxor@gmail.com?part=5
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors
2026-08-12 23:33 ` [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors Kumar Kartikeya Dwivedi
@ 2026-08-12 23:58 ` sashiko-bot
0 siblings, 0 replies; 22+ messages in thread
From: sashiko-bot @ 2026-08-12 23:58 UTC (permalink / raw)
To: Kumar Kartikeya Dwivedi; +Cc: bpf
Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] Uninitialized variable `ref_id` used in `check_kfunc_args` for non-pointer release kfunc arguments.
- [Low] Incorrect diagnostic message for kfunc fixed-size memory arguments failing bounds checks.
--
--- Patch [11]: [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors ---
commit ea19a04c0e142c86cd13b8e8524d76e024167249
Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>
bpf: Report Call Type Safety argument errors
Augment selected helper and kfunc argument-contract failures with Call Type
Safety reports. Keep the existing terse verifier messages and add reason,
source context, causal register or stack-argument history, and targeted
suggestions.
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 24ae3cb38f6d8..7e28f4d9f5c4d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -12361,29 +12437,43 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
>
> t = btf_type_skip_modifiers(btf, args[i].type, NULL);
>
> - if (btf_type_is_ptr(t) && (bpf_register_is_null(reg) || type_may_be_null(reg->type)) &&
> + if (btf_type_is_ptr(t)) {
> + ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
> + ref_tname = btf_name_by_offset(btf, ref_t->name_off);
> + }
> +
> + if (btf_type_is_ptr(t) &&
> + (bpf_register_is_null(reg) || type_may_be_null(reg->type)) &&
> !type_may_be_null(kf_arg_type)) {
[ ... ]
> }
>
> if (regno == meta->release_regno && !is_kfunc_arg_dynptr(meta->btf, &args[i]) &&
> !reg_is_referenced(env, reg) && !bpf_register_is_null(reg)) {
> + const char *expected_type;
> +
> + expected_type = diag_btf_type_name(env, btf, ref_id);
[Severity: Medium]
Could this result in using an uninitialized ref_id? If a module registers a
kfunc with KF_RELEASE that takes a non-pointer argument, btf_type_is_ptr(t)
would be false, skipping the initialization of ref_id.
Then, on the release argument mismatch path here, diag_btf_type_name() would
read uninitialized stack memory from ref_id, which might lead to out-of-bounds
reads in btf_type_by_id() or leak stack contents into the verifier log.
[ ... ]
> @@ -12706,8 +12863,17 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
> return -EINVAL;
> }
> ret = check_mem_reg(env, reg, argno, type_size, BPF_READ | BPF_WRITE, meta);
> - if (ret < 0)
> + if (ret < 0) {
> + const char *expected_type;
> +
> + expected_type = diag_btf_type_name(env, btf, ref_id);
> + diag_call_arg_fmt(env, insn_idx, argno, func_name,
> + "Pass stack, map, context, or other verifier-known memory of the expected type and size, not an integer cast to a pointer.",
> + "the kfunc expects %u bytes of memory for %s, but it is %s and not verifier-known memory",
> + type_size, expected_type,
> + bpf_diag_reg_type_plain(env, reg->type));
[Severity: Low]
Does this emit a misleading diagnostic when the bounds check fails? If a kfunc
takes a fixed-size memory argument and the BPF program passes a valid
verifier-known memory pointer (like PTR_TO_STACK) but the buffer is too small,
check_mem_reg() returns an error.
This diagnostic would then unconditionally claim the argument is "not
verifier-known memory" and advise not to pass an "integer cast to a pointer",
which obscures the actual bounds-check issue.
> return ret;
> + }
> }
> break;
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260812233326.3575958-1-memxor@gmail.com?part=11
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context
2026-08-12 23:33 ` [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context Kumar Kartikeya Dwivedi
@ 2026-08-13 0:15 ` sashiko-bot
0 siblings, 0 replies; 22+ messages in thread
From: sashiko-bot @ 2026-08-13 0:15 UTC (permalink / raw)
To: Kumar Kartikeya Dwivedi; +Cc: bpf
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] bpf_disasm_kfunc_name() will trigger a NULL pointer dereference or mutate verifier state if diagnostic formatting is invoked before the add_kfuncs() pass completes.
--
--- Patch [2]: [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context ---
commit ef91626322111071ba03bd2ef6640700c748dd5f
Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>
bpf: Add source and instruction diagnostic context
Teach verifier diagnostics to annotate an instruction with BTF source
line information and nearby BPF instructions. The renderer keeps source
text in a fixed-width lane and prints instructions in a stable right-hand
gutter.
> diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
> --- a/kernel/bpf/diagnostics.c
> +++ b/kernel/bpf/diagnostics.c
[ ... ]
> @@ -35,6 +245,182 @@ static void diag_write(struct bpf_verifier_env *env, const char *fmt, ...)
[ ... ]
> +static const char *disasm_kfunc_name(void *private_data, const struct bpf_insn *insn)
> +{
> + struct disasm_ctx *ctx = private_data;
> +
> + return bpf_disasm_kfunc_name(ctx->env, insn);
> +}
> +
> +static void format_disasm_line(struct bpf_verifier_env *env, int insn_idx,
> + struct disasm_line *line)
> +{
> + struct disasm_ctx ctx = { .env = env };
> + struct bpf_insn *insn;
> + const struct bpf_insn_cbs cbs = {
> + .cb_call = disasm_kfunc_name,
> + .cb_print = disasm_print,
> + .private_data = &ctx,
> + };
[Severity: High]
Can this sequence trigger a NULL pointer dereference or unsafe state
mutation?
If bpf_diag_source() handles an error during early structural validation
(before add_kfuncs() runs), it calls format_disasm_line() to print nearby
context instructions.
If any instruction in this window is a module kfunc call, it invokes the
bpf_disasm_kfunc_name() callback shown above, which eventually cascades into
__find_kfunc_desc_btf() in kernel/bpf/verifier.c.
__find_kfunc_desc_btf() then executes:
tab = env->prog->aux->kfunc_btf_tab;
b = bsearch(&kf_btf, tab->descs, tab->nr_descs, ...);
If the kfunc BTF table hasn't been allocated yet, wouldn't dereferencing
tab cause a panic?
Additionally, if the table is only partially initialized, wouldn't
__find_kfunc_desc_btf() mutate the table by appending and sorting new
entries during what is expected to be a read-only logging operation?
> +
> + line->idx = insn_idx;
> + line->valid = false;
> + seq_buf_init(&ctx.seq, line->text, sizeof(line->text));
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260812233326.3575958-1-memxor@gmail.com?part=2
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH bpf-next v4 00/16] Redesign Verification Errors
2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
` (15 preceding siblings ...)
2026-08-12 23:33 ` [PATCH bpf-next v4 16/16] bpf: Gate verifier diagnostics on log level Kumar Kartikeya Dwivedi
@ 2026-08-13 1:38 ` Eduard Zingerman
16 siblings, 0 replies; 22+ messages in thread
From: Eduard Zingerman @ 2026-08-13 1:38 UTC (permalink / raw)
To: Kumar Kartikeya Dwivedi, bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
Emil Tsalapatis, kkd, kernel-team
On Thu, 2026-08-13 at 01:33 +0200, Kumar Kartikeya Dwivedi wrote:
> TL;DR: This set reworks verifier error messages to include source and
> instruction annotations, together with more causal context, making
> failures easier to understand and more actionable when debugging and
> repairing BPF programs.
This series is in conflict with
14c950ac2be8 ("bpf: Track verifier instruction stats for each subprogram")
^ permalink raw reply [flat|nested] 22+ messages in thread
end of thread, other threads:[~2026-08-13 1:38 UTC | newest]
Thread overview: 22+ messages (download: mbox.gz follow: Atom feed
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2026-08-12 23:33 [PATCH bpf-next v4 00/16] Redesign Verification Errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 01/16] bpf: Add verifier diagnostics report helpers Kumar Kartikeya Dwivedi
2026-08-12 23:41 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 02/16] bpf: Add source and instruction diagnostic context Kumar Kartikeya Dwivedi
2026-08-13 0:15 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 03/16] bpf: Add verifier diagnostic event log Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 04/16] bpf: Prune verifier diagnostics when switching paths Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 05/16] bpf: Track verifier register diagnostic events Kumar Kartikeya Dwivedi
2026-08-12 23:53 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 06/16] bpf: Track verifier reference " Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 07/16] bpf: Track verifier context " Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 08/16] bpf: Report Register Type Safety errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 09/16] bpf: Report Memory Safety bounds errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 10/16] bpf: Report Resource Lifetime reference leaks Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 11/16] bpf: Report Call Type Safety argument errors Kumar Kartikeya Dwivedi
2026-08-12 23:58 ` sashiko-bot
2026-08-12 23:33 ` [PATCH bpf-next v4 12/16] bpf: Report Execution Context Safety errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 13/16] bpf: Report Program Structure CFG errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 14/16] bpf: Report Policy helper and kfunc errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 15/16] bpf: Report Verifier Limit errors Kumar Kartikeya Dwivedi
2026-08-12 23:33 ` [PATCH bpf-next v4 16/16] bpf: Gate verifier diagnostics on log level Kumar Kartikeya Dwivedi
2026-08-13 1:38 ` [PATCH bpf-next v4 00/16] Redesign Verification Errors Eduard Zingerman
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