bpf: mark a NULL BTF_ID argument of a global subprogram precise

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btf_check_func_arg_match() accepts a NULL register for an
ARG_PTR_TO_BTF_ID argument tagged __arg_nullable and skips
check_reg_type() and check_func_arg_reg_off() without marking the
register precise. Hence a checkpoint created on such a path would
prune against arbitrary scalar value.

Fixes: e2b3c4ff5d ("bpf: add __arg_trusted global func arg tag")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-7-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Eduard Zingerman 2026-09-04 17:05:58 -07:00 • committed by Alexei Starovoitov

parent 562d266d3f

commit e726fc6b9a

1 changed files with 5 additions and 1 deletions

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kernel/bpf/verifier.c

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