From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH bpf-next v2 22/31] libbpf: Fix unbounded memory access in bpf_usdt_arg()
Date: Sat, 28 Jan 2023 01:06:41 +0100 [thread overview]
Message-ID: <20230128000650.1516334-23-iii@linux.ibm.com> (raw)
In-Reply-To: <20230128000650.1516334-1-iii@linux.ibm.com>
Loading programs that use bpf_usdt_arg() on s390x fails with:
; if (arg_num >= BPF_USDT_MAX_ARG_CNT || arg_num >= spec->arg_cnt)
128: (79) r1 = *(u64 *)(r10 -24) ; frame1: R1_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
129: (25) if r1 > 0xb goto pc+83 ; frame1: R1_w=scalar(umax=11,var_off=(0x0; 0xf))
...
; arg_spec = &spec->args[arg_num];
135: (79) r1 = *(u64 *)(r10 -24) ; frame1: R1_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
...
; switch (arg_spec->arg_type) {
139: (61) r1 = *(u32 *)(r2 +8)
R2 unbounded memory access, make sure to bounds check any such access
The reason is that, even though the C code enforces that
arg_num < BPF_USDT_MAX_ARG_CNT, the verifier cannot propagate this
constraint to the arg_spec assignment yet. Help it by forcing r1 back
to stack after comparison.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
tools/lib/bpf/usdt.bpf.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/usdt.bpf.h b/tools/lib/bpf/usdt.bpf.h
index fdfd235e52c4..0bd4c135acc2 100644
--- a/tools/lib/bpf/usdt.bpf.h
+++ b/tools/lib/bpf/usdt.bpf.h
@@ -130,7 +130,10 @@ int bpf_usdt_arg(struct pt_regs *ctx, __u64 arg_num, long *res)
if (!spec)
return -ESRCH;
- if (arg_num >= BPF_USDT_MAX_ARG_CNT || arg_num >= spec->arg_cnt)
+ if (arg_num >= BPF_USDT_MAX_ARG_CNT)
+ return -ENOENT;
+ barrier_var(arg_num);
+ if (arg_num >= spec->arg_cnt)
return -ENOENT;
arg_spec = &spec->args[arg_num];
--
2.39.1
next prev parent reply other threads:[~2023-01-28 0:07 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-28 0:06 [PATCH bpf-next v2 00/31] Support bpf trampoline for s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 01/31] bpf: Use ARG_CONST_SIZE_OR_ZERO for 3rd argument of bpf_tcp_raw_gen_syncookie_ipv{4,6}() Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 02/31] bpf: Change BPF_MAX_TRAMP_LINKS to enum Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 03/31] selftests/bpf: Query BPF_MAX_TRAMP_LINKS using BTF Ilya Leoshkevich
2023-01-28 20:49 ` Alexei Starovoitov
2023-01-29 1:50 ` Alexei Starovoitov
2023-01-28 0:06 ` [PATCH bpf-next v2 04/31] selftests/bpf: Fix liburandom_read.so linker error Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 05/31] selftests/bpf: Fix symlink creation error Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 06/31] selftests/bpf: Fix kfree_skb on s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 07/31] selftests/bpf: Set errno when urand_spawn() fails Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 08/31] selftests/bpf: Fix decap_sanity_ns cleanup Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 09/31] selftests/bpf: Fix verify_pkcs7_sig on s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 10/31] selftests/bpf: Fix xdp_do_redirect " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 11/31] selftests/bpf: Fix cgrp_local_storage " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 12/31] selftests/bpf: Check stack_mprotect() return value Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 13/31] selftests/bpf: Increase SIZEOF_BPF_LOCAL_STORAGE_ELEM on s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 14/31] selftests/bpf: Add a sign-extension test for kfuncs Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 15/31] selftests/bpf: Fix test_lsm on s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 16/31] selftests/bpf: Fix test_xdp_adjust_tail_grow2 " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 17/31] selftests/bpf: Fix vmlinux test " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 18/31] selftests/bpf: Fix sk_assign " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 19/31] selftests/bpf: Fix xdp_synproxy/tc " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 20/31] selftests/bpf: Fix profiler " Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 21/31] libbpf: Simplify barrier_var() Ilya Leoshkevich
2023-01-28 0:06 ` Ilya Leoshkevich [this message]
2023-01-28 0:06 ` [PATCH bpf-next v2 23/31] libbpf: Fix BPF_PROBE_READ{_STR}_INTO() on s390x Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 24/31] bpf: iterators: Split iterators.lskel.h into little- and big- endian versions Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 25/31] bpf: btf: Add BTF_FMODEL_SIGNED_ARG flag Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 26/31] s390/bpf: Fix a typo in a comment Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 27/31] s390/bpf: Add expoline to tail calls Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 28/31] s390/bpf: Implement bpf_arch_text_poke() Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 29/31] s390/bpf: Implement arch_prepare_bpf_trampoline() Ilya Leoshkevich
2023-01-28 8:37 ` kernel test robot
2023-01-28 0:06 ` [PATCH bpf-next v2 30/31] s390/bpf: Implement bpf_jit_supports_subprog_tailcalls() Ilya Leoshkevich
2023-01-28 0:06 ` [PATCH bpf-next v2 31/31] s390/bpf: Implement bpf_jit_supports_kfunc_call() Ilya Leoshkevich
2023-01-28 20:50 ` [PATCH bpf-next v2 00/31] Support bpf trampoline for s390x patchwork-bot+netdevbpf
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