linux-kernel - [PATCH bpf-next v2 07/16] bpf: verifier: bail out if the argument is not a map

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Message-Id: <20240420-bpf_wq-v2-7-6c986a5a741f@kernel.org>
Date: Sat, 20 Apr 2024 11:09:07 +0200
From: Benjamin Tissoires <bentiss@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, 
 Shuah Khan <shuah@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, Benjamin Tissoires <bentiss@...nel.org>
Subject: [PATCH bpf-next v2 07/16] bpf: verifier: bail out if the argument
 is not a map

When a kfunc is declared with a KF_ARG_PTR_TO_MAP, we should have
reg->map_ptr set to a non NULL value, otherwise, that means that the
underlying type is not a map.

Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>

---

new in v2
---
 kernel/bpf/verifier.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index deaf2e1ab690..b95fd63864f1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11720,6 +11720,11 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 		case KF_ARG_PTR_TO_NULL:
 			continue;
 		case KF_ARG_PTR_TO_MAP:
+			if (!reg->map_ptr) {
+				verbose(env, "pointer in R%d isn't map pointer\n", regno);
+				return -EINVAL;
+			}
+			fallthrough;
 		case KF_ARG_PTR_TO_ALLOC_BTF_ID:
 		case KF_ARG_PTR_TO_BTF_ID:
 			if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))

-- 
2.44.0