bpf: mark a NULL kfunc argument precise

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check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b636 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Eduard Zingerman 2026-09-04 17:05:56 -07:00 • committed by Alexei Starovoitov

parent 100f4cc0d5

commit 506ada8962

1 changed files with 5 additions and 1 deletions

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kernel/bpf/verifier.c

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