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Tue, 20 Jan 2026 00:29:45 -0800 (PST) From: Zesen Liu Date: Tue, 20 Jan 2026 16:28:47 +0800 Subject: [PATCH bpf-next v3 2/2] bpf: Require ARG_PTR_TO_MEM with memory flag Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260120-helper_proto-v3-2-27b0180b4e77@gmail.com> References: <20260120-helper_proto-v3-0-27b0180b4e77@gmail.com> In-Reply-To: <20260120-helper_proto-v3-0-27b0180b4e77@gmail.com> To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Matt Bobrowski , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Daniel Xu Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, netdev@vger.kernel.org, Shuran Liu , Peili Gao , Haoran Ni , Zesen Liu X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1777; i=ftyghome@gmail.com; h=from:subject:message-id; bh=8Tr89emgP1ROOH9GbGP0Co4KFsZQ9rj/qDR8RDJcrCE=; b=owGbwMvMwCXWI1/u+8bXqJ3xtFoSQ2a+zZPdOu4shwxU65gnZc/9H6v72XNH73qxA/f3nCjI/ KC4tzS4o5SFQYyLQVZMkaX3h+HdlZnmxttsFhyEmcPKBDKEgYtTACay+RLDP63fKzmaflfPbI9d vEWyNH9pnRaT1Zz1uxjq5uga2U88wc/I8E543p/Yg6kLZwtHsR2sV1z0vLtNL5B3bQDzdEW1SVM ruQE= X-Developer-Key: i=ftyghome@gmail.com; a=openpgp; fpr=8DF831DDA9693733B63CA0C18C1F774DEC4D3287 Add check to ensure that ARG_PTR_TO_MEM is used with either MEM_WRITE or MEM_RDONLY. Using ARG_PTR_TO_MEM alone without flags does not make sense because: - If the helper does not change the argument, missing MEM_RDONLY causes the verifier to incorrectly reject a read-only buffer. - If the helper does change the argument, missing MEM_WRITE causes the verifier to incorrectly assume the memory is unchanged, leading to errors in code optimization. Co-developed-by: Shuran Liu Signed-off-by: Shuran Liu Co-developed-by: Peili Gao Signed-off-by: Peili Gao Co-developed-by: Haoran Ni Signed-off-by: Haoran Ni Signed-off-by: Zesen Liu Reviewed-by: Eduard Zingerman --- kernel/bpf/verifier.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9de0ec0c3ed9..a89f5bc7eff7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10351,10 +10351,27 @@ static bool check_btf_id_ok(const struct bpf_func= _proto *fn) return true; } =20 +static bool check_mem_arg_rw_flag_ok(const struct bpf_func_proto *fn) +{ + int i; + + for (i =3D 0; i < ARRAY_SIZE(fn->arg_type); i++) { + enum bpf_arg_type arg_type =3D fn->arg_type[i]; + + if (base_type(arg_type) !=3D ARG_PTR_TO_MEM) + continue; + if (!(arg_type & (MEM_WRITE | MEM_RDONLY))) + return false; + } + + return true; +} + static int check_func_proto(const struct bpf_func_proto *fn) { return check_raw_mode_ok(fn) && check_arg_pair_ok(fn) && + check_mem_arg_rw_flag_ok(fn) && check_btf_id_ok(fn) ? 0 : -EINVAL; } =20 --=20 2.43.0