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[209.85.218.48]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a68f4da980esm288070666b.203.2024.06.03.14.42.27 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Jun 2024 14:42:27 -0700 (PDT) Received: by mail-ej1-f48.google.com with SMTP id a640c23a62f3a-a6267778b3aso436309666b.3 for ; Mon, 03 Jun 2024 14:42:27 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCVykRsBjEy5qpuLDQ6UmbXMK4cxWWV3SaKoNXQw8AZQGyvNzPS3M+8kGwD3uA0Wvv764FPWHsQUdZfGck4mYx3kvFU= X-Received: by 2002:a17:907:9482:b0:a68:c6c1:cd63 with SMTP id a640c23a62f3a-a68c6c1d466mr478691866b.13.1717450947222; Mon, 03 Jun 2024 14:42:27 -0700 (PDT) MIME-Version: 1.0 References: <20240602023754.25443-1-laoar.shao@gmail.com> <20240602023754.25443-3-laoar.shao@gmail.com> <20240603172008.19ba98ff@gandalf.local.home> In-Reply-To: <20240603172008.19ba98ff@gandalf.local.home> From: Linus Torvalds Date: Mon, 3 Jun 2024 14:42:10 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/6] tracing: Replace memcpy() with __get_task_comm() To: Steven Rostedt Cc: Yafang Shao , 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, Masami Hiramatsu , Mathieu Desnoyers Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1C093180006 X-Stat-Signature: bkdgji4bk71wickra9tph7zbawphijr3 X-HE-Tag: 1717450950-800482 X-HE-Meta: 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 XECi7ecZ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.026179, 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, 3 Jun 2024 at 14:19, Steven Rostedt wrote: > > - __array( char, comm, TASK_COMM_LEN ) > + __string( comm, strlen(comm) ) Is this actually safe is 'comm[]' is being modified at the same time? The 'strlen()' will not be consistent with the string copy. Because that is very much the case. It's not a stable source. For example, strlen() may return 5. But by the time you then actually copy the data, the string may have changed, and there would not necessarily be a NUL character at comm[5] any more. It might be further in the string, or it might be earlier. Linus