selftests/bpf: add test case for BPF LSM hook bpf_lsm_mmap_file

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Add a trivial test case asserting that the BPF verifier enforces
PTR_MAYBE_NULL semantics on the struct file pointer argument of BPF
LSM hook bpf_lsm_mmap_file().

Dereferencing the struct file pointer passed into bpf_lsm_mmap_file()
without explicitly performing a NULL check first should not be
permitted by the BPF verifier as it can lead to NULL pointer
dereferences and a kernel crash.

Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20251216133000.3690723-2-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Matt Bobrowski 2025-12-16 13:30:00 +00:00 • committed by Alexei Starovoitov

parent 94e948b7e6

commit d2749ae85a

1 changed files with 30 additions and 1 deletions

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tools/testing/selftests/bpf/progs/verifier_lsm.c

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