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([2620:10d:c090:500::aa81]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b6b3503ce3sm14350271eec.12.2026.01.19.12.25.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jan 2026 12:25:11 -0800 (PST) Message-ID: <600177c05c552f470cc5e25c7dba6990d96790e9.camel@gmail.com> Subject: Re: [PATCH bpf RESEND v2 2/2] bpf: Require ARG_PTR_TO_MEM with memory flag From: Eduard Zingerman To: Zesen Liu , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , 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 Date: Mon, 19 Jan 2026 12:25:08 -0800 In-Reply-To: <20260118-helper_proto-v2-2-ab3a1337e755@gmail.com> References: <20260118-helper_proto-v2-0-ab3a1337e755@gmail.com> <20260118-helper_proto-v2-2-ab3a1337e755@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sun, 2026-01-18 at 16:16 +0800, Zesen Liu wrote: > Add check to ensure that ARG_PTR_TO_MEM is used with either MEM_WRITE or > MEM_RDONLY. >=20 > Using ARG_PTR_TO_MEM alone without tags does not make sense because: >=20 > - If the helper does not change the argument, missing MEM_RDONLY causes t= he > 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. >=20 > 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 > --- Note: this patch no longer applies properly because of the change in the check_func_proto() signature. 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