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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4907e6a60c4sm19108485e9.1.2026.05.27.01.42.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 01:42:23 -0700 (PDT) Date: Wed, 27 May 2026 09:42:21 +0100 From: David Laight To: Steven Rostedt Cc: =?UTF-8?B?QW5kcsOp?= Almeida , Peter Zijlstra , Juri Lelli , Vincent Guittot , Christian Brauner , Kees Cook , Shuah Khan , willy@infradead.org, mathieu.desnoyers@efficios.com, Linus Torvalds , akpm@linux-foundation.org, Yafang Shao , andrii.nakryiko@gmail.com, arnaldo.melo@gmail.com, Petr Mladek , linux-kernel@vger.kernel.org, kernel-dev@igalia.com, linux-mm@kvack.org, linux-api@vger.kernel.org, Bhupesh Subject: Re: [PATCH v2 4/6] sched: Extend task command name to 64 bytes Message-ID: <20260527094221.2f5b49d9@pumpkin> In-Reply-To: <20260526123103.4facbaed@gandalf.local.home> References: <20260524-tonyk-long_name-v2-0-332f6bd041c4@igalia.com> <20260524-tonyk-long_name-v2-4-332f6bd041c4@igalia.com> <20260525114107.7fa5b4c1@pumpkin> <20260525114241.4b6f3050@pumpkin> <20260526123103.4facbaed@gandalf.local.home> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 26 May 2026 12:31:03 -0400 Steven Rostedt wrote: > On Mon, 25 May 2026 11:42:41 +0100 > David Laight wrote: > > > > > error = security_task_prctl(option, arg2, arg3, arg4, arg5); > > > > @@ -2601,16 +2601,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > > > > error = -EINVAL; > > > > break; > > > > case PR_SET_NAME: > > > > - comm[sizeof(me->comm) - 1] = 0; > > > > + comm[TASK_COMM_LEN - 1] = 0; > > > > if (strncpy_from_user(comm, (char __user *)arg2, > > > > - sizeof(me->comm) - 1) < 0) > > > > + TASK_COMM_LEN - 1) < 0) > > > > > > Nak - you can't do that. > > > You are reading data that the application doesn't expect you to read. > > > > Or have I got confused over the names... > > You may have gotten confused by names, as sizeof(me->comm) is the same as > TASK_COMM_LEN. Basically, the above doesn't change anything. The name of the patch doesn't help: sched: Extend task command name to 64 bytes If you want to catch/check all the uses I suspect that all the occurrences of TASK_COMM_LEN need changing. For clarity this one should probably be TASK_COMM_LEN_OLD. (that might be problematic for the uapi headers) -- David > > -- Steve