[PATCH AUTOSEL 5.4 02/31] selftests/bpf: satisfy compiler by having explicit return in btf test

[PATCH AUTOSEL 5.4 02/31] selftests/bpf: satisfy compiler by having explicit return in btf test

[Sasha Levin]

From: Andrii Nakryiko <andrii@kernel.org>

[ Upstream commit f4c7e887324f5776eef6e6e47a90e0ac8058a7a8 ]

Some compilers complain about get_pprint_mapv_size() not returning value
in some code paths. Fix with explicit return.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/testing/selftests/bpf/test_btf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index f641eb292a88..a821ff121e03 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -4663,6 +4663,7 @@ static size_t get_pprint_mapv_size(enum pprint_mapv_kind_t mapv_kind)
 #endif
 
 	assert(0);
+	return 0;
 }
 
 static void set_pprint_mapv(enum pprint_mapv_kind_t mapv_kind,
-- 
2.43.0

[PATCH AUTOSEL 5.4 03/31] selftests/bpf: Fix pyperf180 compilation failure with clang18

[Sasha Levin]

From: Yonghong Song <yonghong.song@linux.dev>

[ Upstream commit 100888fb6d8a185866b1520031ee7e3182b173de ]

With latest clang18 (main branch of llvm-project repo), when building bpf selftests,
    [~/work/bpf-next (master)]$ make -C tools/testing/selftests/bpf LLVM=1 -j

The following compilation error happens:
    fatal error: error in backend: Branch target out of insn range
    ...
    Stack dump:
    0.      Program arguments: clang -g -Wall -Werror -D__TARGET_ARCH_x86 -mlittle-endian
      -I/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include
      -I/home/yhs/work/bpf-next/tools/testing/selftests/bpf -I/home/yhs/work/bpf-next/tools/include/uapi
      -I/home/yhs/work/bpf-next/tools/testing/selftests/usr/include -idirafter
      /home/yhs/work/llvm-project/llvm/build.18/install/lib/clang/18/include -idirafter /usr/local/include
      -idirafter /usr/include -Wno-compare-distinct-pointer-types -DENABLE_ATOMICS_TESTS -O2 --target=bpf
      -c progs/pyperf180.c -mcpu=v3 -o /home/yhs/work/bpf-next/tools/testing/selftests/bpf/pyperf180.bpf.o
    1.      <eof> parser at end of file
    2.      Code generation
    ...

The compilation failure only happens to cpu=v2 and cpu=v3. cpu=v4 is okay
since cpu=v4 supports 32-bit branch target offset.

The above failure is due to upstream llvm patch [1] where some inlining behavior
are changed in clang18.

To workaround the issue, previously all 180 loop iterations are fully unrolled.
The bpf macro __BPF_CPU_VERSION__ (implemented in clang18 recently) is used to avoid
unrolling changes if cpu=v4. If __BPF_CPU_VERSION__ is not available and the
compiler is clang18, the unrollng amount is unconditionally reduced.

  [1] https://github.com/llvm/llvm-project/commit/1a2e77cf9e11dbf56b5720c607313a566eebb16e

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/testing/selftests/bpf/progs/pyperf180.c | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/pyperf180.c b/tools/testing/selftests/bpf/progs/pyperf180.c
index c39f559d3100..42c4a8b62e36 100644
--- a/tools/testing/selftests/bpf/progs/pyperf180.c
+++ b/tools/testing/selftests/bpf/progs/pyperf180.c
@@ -1,4 +1,26 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2019 Facebook
 #define STACK_MAX_LEN 180
+
+/* llvm upstream commit at clang18
+ *   https://github.com/llvm/llvm-project/commit/1a2e77cf9e11dbf56b5720c607313a566eebb16e
+ * changed inlining behavior and caused compilation failure as some branch
+ * target distance exceeded 16bit representation which is the maximum for
+ * cpu v1/v2/v3. Macro __BPF_CPU_VERSION__ is later implemented in clang18
+ * to specify which cpu version is used for compilation. So a smaller
+ * unroll_count can be set if __BPF_CPU_VERSION__ is less than 4, which
+ * reduced some branch target distances and resolved the compilation failure.
+ *
+ * To capture the case where a developer/ci uses clang18 but the corresponding
+ * repo checkpoint does not have __BPF_CPU_VERSION__, a smaller unroll_count
+ * will be set as well to prevent potential compilation failures.
+ */
+#ifdef __BPF_CPU_VERSION__
+#if __BPF_CPU_VERSION__ < 4
+#define UNROLL_COUNT 90
+#endif
+#elif __clang_major__ == 18
+#define UNROLL_COUNT 90
+#endif
+
 #include "pyperf.h"
-- 
2.43.0

[PATCH AUTOSEL 5.4 11/31] bpf: Add map and need_defer parameters to .map_fd_put_ptr()

[Sasha Levin]

From: Hou Tao <houtao1@huawei.com>

[ Upstream commit 20c20bd11a0702ce4dc9300c3da58acf551d9725 ]

map is the pointer of outer map, and need_defer needs some explanation.
need_defer tells the implementation to defer the reference release of
the passed element and ensure that the element is still alive before
the bpf program, which may manipulate it, exits.

The following three cases will invoke map_fd_put_ptr() and different
need_defer values will be passed to these callers:

1) release the reference of the old element in the map during map update
   or map deletion. The release must be deferred, otherwise the bpf
   program may incur use-after-free problem, so need_defer needs to be
   true.
2) release the reference of the to-be-added element in the error path of
   map update. The to-be-added element is not visible to any bpf
   program, so it is OK to pass false for need_defer parameter.
3) release the references of all elements in the map during map release.
   Any bpf program which has access to the map must have been exited and
   released, so need_defer=false will be OK.

These two parameters will be used by the following patches to fix the
potential use-after-free problem for map-in-map.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/bpf.h     |  6 +++++-
 kernel/bpf/arraymap.c   | 12 +++++++-----
 kernel/bpf/hashtab.c    |  6 +++---
 kernel/bpf/map_in_map.c |  2 +-
 kernel/bpf/map_in_map.h |  2 +-
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5705cda3c4c4..6107b537245a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -49,7 +49,11 @@ struct bpf_map_ops {
 	/* funcs called by prog_array and perf_event_array map */
 	void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
 				int fd);
-	void (*map_fd_put_ptr)(void *ptr);
+	/* If need_defer is true, the implementation should guarantee that
+	 * the to-be-put element is still alive before the bpf program, which
+	 * may manipulate it, exists.
+	 */
+	void (*map_fd_put_ptr)(struct bpf_map *map, void *ptr, bool need_defer);
 	u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
 	u32 (*map_fd_sys_lookup_elem)(void *ptr);
 	void (*map_seq_show_elem)(struct bpf_map *map, void *key,
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 1c65ce0098a9..81ed9b79f401 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -542,7 +542,7 @@ int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
 
 	old_ptr = xchg(array->ptrs + index, new_ptr);
 	if (old_ptr)
-		map->ops->map_fd_put_ptr(old_ptr);
+		map->ops->map_fd_put_ptr(map, old_ptr, true);
 
 	return 0;
 }
@@ -558,7 +558,7 @@ static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
 
 	old_ptr = xchg(array->ptrs + index, NULL);
 	if (old_ptr) {
-		map->ops->map_fd_put_ptr(old_ptr);
+		map->ops->map_fd_put_ptr(map, old_ptr, true);
 		return 0;
 	} else {
 		return -ENOENT;
@@ -582,8 +582,9 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map,
 	return prog;
 }
 
-static void prog_fd_array_put_ptr(void *ptr)
+static void prog_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
 {
+	/* bpf_prog is freed after one RCU or tasks trace grace period */
 	bpf_prog_put(ptr);
 }
 
@@ -694,8 +695,9 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
 	return ee;
 }
 
-static void perf_event_fd_array_put_ptr(void *ptr)
+static void perf_event_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
 {
+	/* bpf_perf_event is freed after one RCU grace period */
 	bpf_event_entry_free_rcu(ptr);
 }
 
@@ -736,7 +738,7 @@ static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
 	return cgroup_get_from_fd(fd);
 }
 
-static void cgroup_fd_array_put_ptr(void *ptr)
+static void cgroup_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
 {
 	/* cgroup_put free cgrp after a rcu grace period */
 	cgroup_put(ptr);
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 03a67583f6fb..f1dec90f3a52 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -674,7 +674,7 @@ static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)
 
 	if (map->ops->map_fd_put_ptr) {
 		ptr = fd_htab_map_get_ptr(map, l);
-		map->ops->map_fd_put_ptr(ptr);
+		map->ops->map_fd_put_ptr(map, ptr, true);
 	}
 }
 
@@ -1426,7 +1426,7 @@ static void fd_htab_map_free(struct bpf_map *map)
 		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
 			void *ptr = fd_htab_map_get_ptr(map, l);
 
-			map->ops->map_fd_put_ptr(ptr);
+			map->ops->map_fd_put_ptr(map, ptr, false);
 		}
 	}
 
@@ -1467,7 +1467,7 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
 
 	ret = htab_map_update_elem(map, key, &ptr, map_flags);
 	if (ret)
-		map->ops->map_fd_put_ptr(ptr);
+		map->ops->map_fd_put_ptr(map, ptr, false);
 
 	return ret;
 }
diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c
index fab4fb134547..7fe5a73aff07 100644
--- a/kernel/bpf/map_in_map.c
+++ b/kernel/bpf/map_in_map.c
@@ -106,7 +106,7 @@ void *bpf_map_fd_get_ptr(struct bpf_map *map,
 	return inner_map;
 }
 
-void bpf_map_fd_put_ptr(void *ptr)
+void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
 {
 	/* ptr->ops->map_free() has to go through one
 	 * rcu grace period by itself.
diff --git a/kernel/bpf/map_in_map.h b/kernel/bpf/map_in_map.h
index a507bf6ef8b9..d296890813cc 100644
--- a/kernel/bpf/map_in_map.h
+++ b/kernel/bpf/map_in_map.h
@@ -15,7 +15,7 @@ bool bpf_map_meta_equal(const struct bpf_map *meta0,
 			const struct bpf_map *meta1);
 void *bpf_map_fd_get_ptr(struct bpf_map *map, struct file *map_file,
 			 int ufd);
-void bpf_map_fd_put_ptr(void *ptr);
+void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer);
 u32 bpf_map_fd_sys_lookup_elem(void *ptr);
 
 #endif
-- 
2.43.0

Re: [PATCH AUTOSEL 5.4 11/31] bpf: Add map and need_defer parameters to .map_fd_put_ptr()

[Hou Tao]

Hi Sasha,

On 1/17/2024 4:02 AM, Sasha Levin wrote:
> From: Hou Tao <houtao1@huawei.com>
>
> [ Upstream commit 20c20bd11a0702ce4dc9300c3da58acf551d9725 ]
>
> map is the pointer of outer map, and need_defer needs some explanation.
> need_defer tells the implementation to defer the reference release of
> the passed element and ensure that the element is still alive before
> the bpf program, which may manipulate it, exits.
>
> The following three cases will invoke map_fd_put_ptr() and different
> need_defer values will be passed to these callers:
>
> 1) release the reference of the old element in the map during map update
>    or map deletion. The release must be deferred, otherwise the bpf
>    program may incur use-after-free problem, so need_defer needs to be
>    true.
> 2) release the reference of the to-be-added element in the error path of
>    map update. The to-be-added element is not visible to any bpf
>    program, so it is OK to pass false for need_defer parameter.
> 3) release the references of all elements in the map during map release.
>    Any bpf program which has access to the map must have been exited and
>    released, so need_defer=false will be OK.
>
> These two parameters will be used by the following patches to fix the
> potential use-after-free problem for map-in-map.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

The patch is just a preparatory patch for fix, please drop it.

[PATCH AUTOSEL 5.4 28/31] libbpf: Fix NULL pointer dereference in bpf_object__collect_prog_relos

[Sasha Levin]

From: Mingyi Zhang <zhangmingyi5@huawei.com>

[ Upstream commit fc3a5534e2a8855427403113cbeb54af5837bbe0 ]

An issue occurred while reading an ELF file in libbpf.c during fuzzing:

	Program received signal SIGSEGV, Segmentation fault.
	0x0000000000958e97 in bpf_object.collect_prog_relos () at libbpf.c:4206
	4206 in libbpf.c
	(gdb) bt
	#0 0x0000000000958e97 in bpf_object.collect_prog_relos () at libbpf.c:4206
	#1 0x000000000094f9d6 in bpf_object.collect_relos () at libbpf.c:6706
	#2 0x000000000092bef3 in bpf_object_open () at libbpf.c:7437
	#3 0x000000000092c046 in bpf_object.open_mem () at libbpf.c:7497
	#4 0x0000000000924afa in LLVMFuzzerTestOneInput () at fuzz/bpf-object-fuzzer.c:16
	#5 0x000000000060be11 in testblitz_engine::fuzzer::Fuzzer::run_one ()
	#6 0x000000000087ad92 in tracing::span::Span::in_scope ()
	#7 0x00000000006078aa in testblitz_engine::fuzzer::util::walkdir ()
	#8 0x00000000005f3217 in testblitz_engine::entrypoint::main::{{closure}} ()
	#9 0x00000000005f2601 in main ()
	(gdb)

scn_data was null at this code(tools/lib/bpf/src/libbpf.c):

	if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {

The scn_data is derived from the code above:

	scn = elf_sec_by_idx(obj, sec_idx);
	scn_data = elf_sec_data(obj, scn);

	relo_sec_name = elf_sec_str(obj, shdr->sh_name);
	sec_name = elf_sec_name(obj, scn);
	if (!relo_sec_name || !sec_name)// don't check whether scn_data is NULL
		return -EINVAL;

In certain special scenarios, such as reading a malformed ELF file,
it is possible that scn_data may be a null pointer

Signed-off-by: Mingyi Zhang <zhangmingyi5@huawei.com>
Signed-off-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Changye Wu <wuchangye@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231221033947.154564-1-liuxin350@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/lib/bpf/libbpf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b8849812449c..4a62a4f051df 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1497,6 +1497,8 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
 
 	bpf_object__sanitize_btf(obj);
 	bpf_object__sanitize_btf_ext(obj);
+	if (!scn_data)
+		return -LIBBPF_ERRNO__FORMAT;
 
 	err = btf__load(obj->btf);
 	if (err) {
-- 
2.43.0