From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F10CC433F5 for ; Wed, 13 Oct 2021 10:24:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17AC7610C8 for ; Wed, 13 Oct 2021 10:24:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239353AbhJMK0Q (ORCPT ); Wed, 13 Oct 2021 06:26:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239350AbhJMK0F (ORCPT ); Wed, 13 Oct 2021 06:26:05 -0400 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC4AAC06174E for ; Wed, 13 Oct 2021 03:24:02 -0700 (PDT) Received: by mail-pg1-x530.google.com with SMTP id 75so1885494pga.3 for ; Wed, 13 Oct 2021 03:24:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=OqWS0xdYApsn9gllT1tysMteOZDpfGt2y2/S2w2k+qg=; b=cdwMZ1ftAXU95xo0VixXXHVfRZ/yHx7zFJdI+1Y9/L0b1O2h0Q4L0gjZ8KTKyNCDqJ BpGpDNMnvhd9veCX04IRJr3IBs0bDeEOq2WfKgRNazZ9cKrA4Q0JEmL22idNXgpg6uRe Wle8OwCZ/LajAydOM2PtA4aqSSDIbe+yUKSuDbJxnSNoT18nJIvLI7EYqvWlytgM3Mo7 27f+QalnNiZcPCjuxbUx7xR0hahbp603eN9psx5vlZvWCPB8kv0huG6Z4DGM7jc4GoOr 4haxg8H+nYx5sA4H4+2e+jtj46NHiU3QXWmuHMMe3wBv1JQedESTcmHYPCJuq6m+Xefx mXwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=OqWS0xdYApsn9gllT1tysMteOZDpfGt2y2/S2w2k+qg=; b=HXVOxTfL+Q1CNLc1Sm8ikDrqq66P/Y86L1TARydaJGlp3PPH4IXqApuGOYZ7ujpkEu zVep6RDZ5L0RKCr0HsAqXmnvebqkblxwIR8SJngklByIsDQFuof5MU+vbiAmaZ3KsM12 ySDQBrUQO5gPt3XFEwCmx4RZqA4sysqMhabtCLb5Y4ZFsbF4fJ5TJojzLsur8bwdRFeY xUGUUE/Zeh4pEmOia+k3ya739O0NMvSU9/PxUkK4wZHJja5gcZKdo6DTpwrWnIHpUoIv Tf/Kxi3MC6BVuSTQ/DNdLekLCFdte8iSow9Ieo9v0mQyQrnpBe0cjKaIjtYPxIKTZDkG OkzQ== X-Gm-Message-State: AOAM533VwATlOlgjLEFK+3d55R2tFYp6plS4AVGLZSJ1qAcNDeDrbSdY TPrfmG39fGeHDc7uE3c43h0= X-Google-Smtp-Source: ABdhPJzsje2Tz8POLjXmy0RUrVLa95f//pE2W7Id9v0M2RD/HBSqcSZYjaf7knXlYFJpHw4cPZb0Uw== X-Received: by 2002:a65:4689:: with SMTP id h9mr26780378pgr.137.1634120642569; Wed, 13 Oct 2021 03:24:02 -0700 (PDT) Received: from vultr.guest ([144.202.123.152]) by smtp.gmail.com with ESMTPSA id 184sm13900994pfw.49.2021.10.13.03.24.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Oct 2021 03:24:02 -0700 (PDT) From: Yafang Shao To: keescook@chromium.org, rostedt@goodmis.org, peterz@infradead.org, pmladek@suse.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, valentin.schneider@arm.com, mathieu.desnoyers@efficios.com, qiang.zhang@windriver.com, robdclark@chromium.org, christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, davem@davemloft.net, kuba@kernel.org Cc: linux-kernel@vger.kernel.org, Yafang Shao Subject: [PATCH v4 5/5] kernel/kthread: show a warning if kthread's comm is truncated Date: Wed, 13 Oct 2021 10:23:46 +0000 Message-Id: <20211013102346.179642-6-laoar.shao@gmail.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211013102346.179642-1-laoar.shao@gmail.com> References: <20211013102346.179642-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Show a warning if task comm is truncated. Below is the result of my test case: truncated kthread comm:I-am-a-kthread-with-lon, pid:14 by 6 characters Suggested-by: Petr Mladek Signed-off-by: Yafang Shao Reviewed-by: Kees Cook Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Al Viro Cc: Petr Mladek --- kernel/kthread.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 5b37a8567168..46b924c92078 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -399,12 +399,17 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), if (!IS_ERR(task)) { static const struct sched_param param = { .sched_priority = 0 }; char name[TASK_COMM_LEN]; + int len; /* * task is already visible to other tasks, so updating * COMM must be protected. */ - vsnprintf(name, sizeof(name), namefmt, args); + len = vsnprintf(name, sizeof(name), namefmt, args); + if (len >= TASK_COMM_LEN) { + pr_warn("truncated kthread comm:%s, pid:%d by %d characters\n", + name, task->pid, len - TASK_COMM_LEN + 1); + } set_task_comm(task, name); /* * root may have changed our (kthreadd's) priority or CPU mask. -- 2.17.1