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[209.85.218.46]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7de4e7f336sm374286266b.131.2024.08.05.20.10.08 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Aug 2024 20:10:08 -0700 (PDT) Received: by mail-ej1-f46.google.com with SMTP id a640c23a62f3a-a7a8a4f21aeso5245466b.2 for ; Mon, 05 Aug 2024 20:10:08 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCVp56uvtSihVpXo8wBVJahTM0HN7yrwuJ8CkAEmQg06woB3OZlBPHvQD+Jhjoi0J1N5sICbE4RqQ618mVRZdvZTlKE= X-Received: by 2002:a17:907:da9:b0:a6f:4fc8:266b with SMTP id a640c23a62f3a-a7dc4db9f44mr1005005366b.3.1722913808064; Mon, 05 Aug 2024 20:10:08 -0700 (PDT) MIME-Version: 1.0 References: <20240804075619.20804-1-laoar.shao@gmail.com> In-Reply-To: From: Linus Torvalds Date: Mon, 5 Aug 2024 20:09:51 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 0/9] Improve the copy of task comm To: Yafang Shao Cc: akpm@linux-foundation.org, ebiederm@xmission.com, alexei.starovoitov@gmail.com, rostedt@goodmis.org, catalin.marinas@arm.com, penguin-kernel@i-love.sakura.ne.jp, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, audit@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 977984001A X-Stat-Signature: k39buq58k9gdxynp3qzy6t4qj56pppde X-HE-Tag: 1722913811-408434 X-HE-Meta: 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 DUaLQzZ3 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 5 Aug 2024 at 20:01, Yafang Shao wrote: > > One concern about removing the BUILD_BUG_ON() is that if we extend > TASK_COMM_LEN to a larger size, such as 24, the caller with a > hardcoded 16-byte buffer may overflow. No, not at all. Because get_task_comm() - and the replacements - would never use TASK_COMM_LEN. They'd use the size of the *destination*. That's what the code already does: #define get_task_comm(buf, tsk) ({ \ ... __get_task_comm(buf, sizeof(buf), tsk); \ note how it uses "sizeof(buf)". Now, it might be a good idea to also verify that 'buf' is an actual array, and that this code doesn't do some silly "sizeof(ptr)" thing. We do have a helper for that, so we could do something like #define get_task_comm(buf, tsk) \ strscpy_pad(buf, __must_be_array(buf)+sizeof(buf), (tsk)->comm) as a helper macro for this all. (Although I'm not convinced we generally want the "_pad()" version, but whatever). Linus