From: Eduard Zingerman <eddyz87@gmail.com>
To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org
Cc: daniel@iogearbox.net, martin.lau@linux.dev, kernel-team@fb.com,
yonghong.song@linux.dev, eddyz87@gmail.com, memxor@gmail.com
Subject: [PATCH bpf 05/10] bpf: mark a NULL kfunc argument precise
Date: Fri, 4 Sep 2026 17:05:56 -0700 [thread overview]
Message-ID: <20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com> (raw)
In-Reply-To: <20260904-register-is-null-precise-fixes-v1-0-0f5a360ff15d@gmail.com>
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>
---
kernel/bpf/verifier.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b758f2822754..2b3d08097806 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12716,8 +12716,12 @@ 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];
--
2.55.0
next prev parent reply other threads:[~2026-09-05 0:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-05 0:05 [PATCH bpf 00/10] bpf: add missing precision propagation after bpf_register_is_null calls Eduard Zingerman
2026-09-05 0:05 ` [PATCH bpf 01/10] bpf: mark a NULL call argument precise Eduard Zingerman
2026-09-05 0:21 ` sashiko-bot
2026-09-05 0:05 ` [PATCH bpf 02/10] selftests/bpf: precision of a NULL helper argument Eduard Zingerman
2026-09-05 0:05 ` [PATCH bpf 03/10] bpf: mark a NULL memory argument of a call precise Eduard Zingerman
2026-09-05 0:23 ` sashiko-bot
2026-09-05 0:51 ` bot+bpf-ci
2026-09-05 0:05 ` [PATCH bpf 04/10] selftests/bpf: precision of a NULL global subprogram memory argument Eduard Zingerman
2026-09-05 0:51 ` bot+bpf-ci
2026-09-05 0:05 ` Eduard Zingerman [this message]
2026-09-05 0:51 ` [PATCH bpf 05/10] bpf: mark a NULL kfunc argument precise bot+bpf-ci
2026-09-05 0:05 ` [PATCH bpf 06/10] selftests/bpf: precision of a NULL kfunc argument Eduard Zingerman
2026-09-05 0:05 ` [PATCH bpf 07/10] bpf: mark a NULL BTF_ID argument of a global subprogram precise Eduard Zingerman
2026-09-05 0:19 ` sashiko-bot
2026-09-05 0:05 ` [PATCH bpf 08/10] selftests/bpf: precision of a NULL global subprogram BTF_ID argument Eduard Zingerman
2026-09-05 0:06 ` [PATCH bpf 09/10] bpf: propagate mark_chain_precision() errors out of loop_flag_is_zero() Eduard Zingerman
2026-09-05 0:06 ` [PATCH bpf 10/10] bpf: use mark_arg_precision() in check_mem_size_reg() Eduard Zingerman
2026-09-05 0:51 ` bot+bpf-ci
2026-09-05 1:20 ` [PATCH bpf 00/10] bpf: add missing precision propagation after bpf_register_is_null calls patchwork-bot+netdevbpf
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