From nobody Mon Oct 6 06:47:31 2025 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20F832D12EE; Thu, 24 Jul 2025 12:36:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753360605; cv=none; b=s1hEFg8eDqaeljut9M/e9mjjWP+7qB2kU8DxrdbwjQckmO5Og38f8dAK79a3/IFT1hgOD3cybMj0JII+FRiZbQ+A9Mz/k6AZCjNEnlOUTU3rzhM6RkPwM+IkGCcZgNw/YBtQdT3qqsmgRXO9Bb8/snAsbHdEYAd4nCvYlKMNmdo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753360605; c=relaxed/simple; bh=VeT5v2Pw40XZeBkH1YcAjtHPzVong+m1lV6lLWLBH3Y=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=T0WZZPyn0tz1vmGQGI/JRApPsnVfPQR9PJGnaih8HMw3HXgE5igtiYXqlyScXEvD3S6cbgU5DGcP5KiFt/nyt5XTinOZz7HjyG5Zjg7nGH11eHghxjz2gwdZVhiqjqw/O1S3SSXQiNKZ6ys3QL0z3Hgy8zZnrzlc6Bc296NClHE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=GT053E1g; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="GT053E1g" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=xxJuMzxUwX/3/4eueFKaBfV57kSJFTkqTcDBwOHRShE=; b=GT053E1gz6CXBmsRuLUeeUOtpZ 6eA3D/mixw8gzo+maEv5+OIfU9l6l1zpm7hNcECcQc97Y2Uo6qNtBbI9bu7B2qeu4nP2+DbqCect7 +zjIq1AQLb+dEZgY7qaQ2t2VyspHqmP2HsMoVM5BdOlERpTPwBCWEBlgc3/qNCUZ8n9qCihzT9LOi lksslbdaMs5Jqe0IdN1K2iRcqgnMKEunvX7/isGlu7tuUm64o3scA1BrNZUnEgAT3Tdz0XxirNtel jMh2a+QbAIEaP9yGzd0xamYvUdg2OP7Rsa5ZEk4cuNdocvwP1xQ9FqXMie0rBszM3c5oXfuc2GzRD biNb+Xcw==; Received: from [223.233.78.24] (helo=localhost.localdomain) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1uevBf-003BPU-Qi; Thu, 24 Jul 2025 14:36:40 +0200 From: Bhupesh To: akpm@linux-foundation.org Cc: bhupesh@igalia.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, oliver.sang@intel.com, lkp@intel.com, laoar.shao@gmail.com, pmladek@suse.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com, alexei.starovoitov@gmail.com, andrii.nakryiko@gmail.com, mirq-linux@rere.qmqm.pl, peterz@infradead.org, willy@infradead.org, david@redhat.com, viro@zeniv.linux.org.uk, keescook@chromium.org, ebiederm@xmission.com, brauner@kernel.org, jack@suse.cz, mingo@redhat.com, juri.lelli@redhat.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-trace-kernel@vger.kernel.org, kees@kernel.org, torvalds@linux-foundation.org Subject: [PATCH v6 2/3] treewide: Switch memcpy() users of 'task->comm' to a more safer implementation Date: Thu, 24 Jul 2025 18:06:11 +0530 Message-Id: <20250724123612.206110-3-bhupesh@igalia.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20250724123612.206110-1-bhupesh@igalia.com> References: <20250724123612.206110-1-bhupesh@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As Linus mentioned in [1], currently we have several memcpy() use-cases which use 'current->comm' to copy the task name over to local copies. For an example: ... char comm[TASK_COMM_LEN]; memcpy(comm, current->comm, TASK_COMM_LEN); ... These should be modified so that we can later implement approaches to handle the task->comm's 16-byte length limitation (TASK_COMM_LEN) in a more modular way (follow-up patch does the same): ... char comm[TASK_COMM_LEN]; memcpy(comm, current->comm, TASK_COMM_LEN); comm[TASK_COMM_LEN - 1] =3D '\0'; ... The relevant 'memcpy()' users were identified using the following search pattern: $ git grep 'memcpy.*->comm\>' [1]. https://lore.kernel.org/all/CAHk-=3DwjAmmHUg6vho1KjzQi2=3DpsR30+CogFd4= aXrThr2gsiS4g@mail.gmail.com/ Signed-off-by: Bhupesh --- include/linux/coredump.h | 3 ++- include/trace/events/block.h | 5 +++++ include/trace/events/oom.h | 1 + include/trace/events/osnoise.h | 1 + include/trace/events/signal.h | 1 + include/trace/events/task.h | 2 ++ 6 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/coredump.h b/include/linux/coredump.h index 68861da4cf7c..988b233dcc09 100644 --- a/include/linux/coredump.h +++ b/include/linux/coredump.h @@ -54,7 +54,8 @@ extern void vfs_coredump(const kernel_siginfo_t *siginfo); do { \ char comm[TASK_COMM_LEN]; \ /* This will always be NUL terminated. */ \ - memcpy(comm, current->comm, sizeof(comm)); \ + memcpy(comm, current->comm, TASK_COMM_LEN); \ + comm[TASK_COMM_LEN - 1] =3D '\0'; \ printk_ratelimited(Level "coredump: %d(%*pE): " Format "\n", \ task_tgid_vnr(current), (int)strlen(comm), comm, ##__VA_ARGS__); \ } while (0) \ diff --git a/include/trace/events/block.h b/include/trace/events/block.h index 6aa79e2d799c..dfc20fbe389c 100644 --- a/include/trace/events/block.h +++ b/include/trace/events/block.h @@ -214,6 +214,7 @@ DECLARE_EVENT_CLASS(block_rq, blk_fill_rwbs(__entry->rwbs, rq->cmd_flags); __get_str(cmd)[0] =3D '\0'; memcpy(__entry->comm, current->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; ), =20 TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u,%u [%s]", @@ -352,6 +353,7 @@ DECLARE_EVENT_CLASS(block_bio, __entry->nr_sector =3D bio_sectors(bio); blk_fill_rwbs(__entry->rwbs, bio->bi_opf); memcpy(__entry->comm, current->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; ), =20 TP_printk("%d,%d %s %llu + %u [%s]", @@ -435,6 +437,7 @@ TRACE_EVENT(block_plug, =20 TP_fast_assign( memcpy(__entry->comm, current->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; ), =20 TP_printk("[%s]", __entry->comm) @@ -454,6 +457,7 @@ DECLARE_EVENT_CLASS(block_unplug, TP_fast_assign( __entry->nr_rq =3D depth; memcpy(__entry->comm, current->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; ), =20 TP_printk("[%s] %d", __entry->comm, __entry->nr_rq) @@ -505,6 +509,7 @@ TRACE_EVENT(block_split, __entry->new_sector =3D new_sector; blk_fill_rwbs(__entry->rwbs, bio->bi_opf); memcpy(__entry->comm, current->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; ), =20 TP_printk("%d,%d %s %llu / %llu [%s]", diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h index 9f0a5d1482c4..a5641ed4285f 100644 --- a/include/trace/events/oom.h +++ b/include/trace/events/oom.h @@ -24,6 +24,7 @@ TRACE_EVENT(oom_score_adj_update, TP_fast_assign( __entry->pid =3D task->pid; memcpy(__entry->comm, task->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; __entry->oom_score_adj =3D task->signal->oom_score_adj; ), =20 diff --git a/include/trace/events/osnoise.h b/include/trace/events/osnoise.h index 3f4273623801..0321b3f8d532 100644 --- a/include/trace/events/osnoise.h +++ b/include/trace/events/osnoise.h @@ -117,6 +117,7 @@ TRACE_EVENT(thread_noise, =20 TP_fast_assign( memcpy(__entry->comm, t->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; __entry->pid =3D t->pid; __entry->start =3D start; __entry->duration =3D duration; diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h index 1db7e4b07c01..7f490e553db5 100644 --- a/include/trace/events/signal.h +++ b/include/trace/events/signal.h @@ -68,6 +68,7 @@ TRACE_EVENT(signal_generate, __entry->sig =3D sig; TP_STORE_SIGINFO(__entry, info); memcpy(__entry->comm, task->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; __entry->pid =3D task->pid; __entry->group =3D group; __entry->result =3D result; diff --git a/include/trace/events/task.h b/include/trace/events/task.h index af535b053033..4ddf21b69372 100644 --- a/include/trace/events/task.h +++ b/include/trace/events/task.h @@ -22,6 +22,7 @@ TRACE_EVENT(task_newtask, TP_fast_assign( __entry->pid =3D task->pid; memcpy(__entry->comm, task->comm, TASK_COMM_LEN); + __entry->comm[TASK_COMM_LEN - 1] =3D '\0'; __entry->clone_flags =3D clone_flags; __entry->oom_score_adj =3D task->signal->oom_score_adj; ), @@ -45,6 +46,7 @@ TRACE_EVENT(task_rename, =20 TP_fast_assign( memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN); + entry->oldcomm[TASK_COMM_LEN - 1] =3D '\0'; strscpy(entry->newcomm, comm, TASK_COMM_LEN); __entry->oom_score_adj =3D task->signal->oom_score_adj; ), --=20 2.38.1