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| author | Leon Hwang <leon.hwang@linux.dev> | 2024-07-28 19:46:11 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-08-12 15:25:49 -0700 |
| commit | fdad456cbcca739bae1849549c7a999857c56f88 (patch) | |
| tree | f6184a52a06eae30720b7bb1acc88997536c39c0 /include/linux/bpf_verifier.h | |
| parent | d74da846046aeec9333e802f5918bd3261fb5509 (diff) | |
| download | linux-fdad456cbcca739bae1849549c7a999857c56f88.tar.gz linux-fdad456cbcca739bae1849549c7a999857c56f88.tar.bz2 linux-fdad456cbcca739bae1849549c7a999857c56f88.zip | |
bpf: Fix updating attached freplace prog in prog_array map
The commit f7866c358733 ("bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT")
fixed a NULL pointer dereference panic, but didn't fix the issue that
fails to update attached freplace prog to prog_array map.
Since commit 1c123c567fb1 ("bpf: Resolve fext program type when checking map compatibility"),
freplace prog and its target prog are able to tail call each other.
And the commit 3aac1ead5eb6 ("bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach")
sets prog->aux->dst_prog as NULL after attaching freplace prog to its
target prog.
After loading freplace the prog_array's owner type is BPF_PROG_TYPE_SCHED_CLS.
Then, after attaching freplace its prog->aux->dst_prog is NULL.
Then, while updating freplace in prog_array the bpf_prog_map_compatible()
incorrectly returns false because resolve_prog_type() returns
BPF_PROG_TYPE_EXT instead of BPF_PROG_TYPE_SCHED_CLS.
After this patch the resolve_prog_type() returns BPF_PROG_TYPE_SCHED_CLS
and update to prog_array can succeed.
Fixes: f7866c358733 ("bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT")
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20240728114612.48486-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 6503c85b10a3..7b776dae36e5 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -856,8 +856,8 @@ static inline u32 type_flag(u32 type) /* only use after check_attach_btf_id() */ static inline enum bpf_prog_type resolve_prog_type(const struct bpf_prog *prog) { - return (prog->type == BPF_PROG_TYPE_EXT && prog->aux->dst_prog) ? - prog->aux->dst_prog->type : prog->type; + return (prog->type == BPF_PROG_TYPE_EXT && prog->aux->saved_dst_prog_type) ? + prog->aux->saved_dst_prog_type : prog->type; } static inline bool bpf_prog_check_recur(const struct bpf_prog *prog) |