diff options
| author | Eduard Zingerman <eddyz87@gmail.com> | 2026-09-04 17:05:56 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2026-09-04 18:17:30 -0700 |
| commit | 506ada89629ec7059b96ecfb0dc7d33ece0103ca (patch) | |
| tree | 0b07297409b68d2333fb4f0eae7f3b072eb68d4c | |
| parent | 100f4cc0d59be88d2b4d6eb42e51910ea2548d04 (diff) | |
| download | linux-2.6-506ada89629ec7059b96ecfb0dc7d33ece0103ca.tar.gz linux-2.6-506ada89629ec7059b96ecfb0dc7d33ece0103ca.zip | |
bpf: mark a NULL kfunc argument precise
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: 3bda08b63670 ("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>
| -rw-r--r-- | kernel/bpf/verifier.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7926e131b1cb..2117c39ac332 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12733,8 +12733,12 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me if (reg_is_referenced(env, reg)) update_ref_obj(&meta->ref_obj, reg); - if (bpf_register_is_null(reg) && type_may_be_null(kf_arg_type)) + if (bpf_register_is_null(reg) && type_may_be_null(kf_arg_type)) { + ret = mark_arg_precision(env, argno); + if (ret) + return ret; continue; + } if (is_kfunc_arg_map(btf, &args[i])) { ref_id = *reg2btf_ids[CONST_PTR_TO_MAP]; |