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 F2D38C433EF for ; Thu, 14 Oct 2021 01:47:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD4D8611AD for ; Thu, 14 Oct 2021 01:47:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229897AbhJNBtE (ORCPT ); Wed, 13 Oct 2021 21:49:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229660AbhJNBtD (ORCPT ); Wed, 13 Oct 2021 21:49:03 -0400 Received: from mail-wr1-x42f.google.com (mail-wr1-x42f.google.com [IPv6:2a00:1450:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8021FC061570 for ; Wed, 13 Oct 2021 18:46:59 -0700 (PDT) Received: by mail-wr1-x42f.google.com with SMTP id r10so14262427wra.12 for ; Wed, 13 Oct 2021 18:46:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hdr4uO/8YFoSPcjOUHFlKHlEJ1GJYDefEgm7W7Vh5/0=; b=K6FnicxKxwMW+37arAahv73CFmafkAGES+NBZaC4lfJR2wevYmB43oHHXReFbcnxRJ S7PufufFhFMYXZq0WMN4a5xlVzYh+Z34d0uGQeOFAfdcAXuE5FGDf9WaXbTGWnvz/3+b 1A/w9bIBZ/wj/cS0W1pQLSF9MBWJrxB3eKrj1n7Vo1UvT2gqwZ1/159LjVSgeknWec5e SZ8DK2gDbKPa0OA+0GcYC/h1iaAxOGC7CSEvlcPOQBDJIV4Tz3ulS31JRQhUgYpv2/Ns GwMbB+4idXQINMR5L0GCQedt84coRN59NSkidlNjPTn9A6ERwhle4jmtuGEBEL0kEQr6 tLsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=hdr4uO/8YFoSPcjOUHFlKHlEJ1GJYDefEgm7W7Vh5/0=; b=l7AmuttKPfT/WMr9wg8xREYbB6p1/fBBxNEDSfW9AzgVbNJky9knruTBKF1reUQ8fd Qrn0w8q3LHwILzCNR2pUDRAv96nPrHEXb6JWdnCktzamAglY+K+pseL+hTM1wKXkklOz kWZgOI5s9JOL8n2Mv67qgMhHRSuuXj1JNB+6FR4pHKVjc8kUxJMV2vugylCjz018X1vy OvA26k7PVNPNebShM+nFfudHiTx8Id79vXdlua6FzJ+0mDJVQ8OvWSVWssrJ8Bm4awFa 56yWPapRsvr/C0g33mVfDK0ZMdAUeBfQCWUxqDLHZEvNCmRW9n13dvgvcM42w5IZQZaI csbg== X-Gm-Message-State: AOAM530ZMwHcNnLnI6inJEZqeFubbUTQjkBBCdaRwiXNUCiYSo30jxW0 lcUIyYOfx7WIx9qYiRoKWtr0qpbNJk5MXifFX/Y= X-Google-Smtp-Source: ABdhPJyTh1aW9hFWUQ7/0Rc3X5iIAjAS+UbSKFCyXKmaF/CGm09wkf7PljMMzSUpNTc/Ei0abNslvJIuq0+CYdVOtk8= X-Received: by 2002:a05:6000:15c6:: with SMTP id y6mr3167673wry.210.1634176018110; Wed, 13 Oct 2021 18:46:58 -0700 (PDT) MIME-Version: 1.0 References: <20211013102346.179642-1-laoar.shao@gmail.com> <20211013102346.179642-2-laoar.shao@gmail.com> <20211013091104.4ea0e05b@gandalf.local.home> In-Reply-To: <20211013091104.4ea0e05b@gandalf.local.home> From: Yafang Shao Date: Thu, 14 Oct 2021 09:46:21 +0800 Message-ID: Subject: Re: [PATCH v4 1/5] elfcore: use TASK_COMM_LEN instead of 16 in prpsinfo To: Steven Rostedt Cc: Kees Cook , Peter Zijlstra , Petr Mladek , Al Viro , Andrew Morton , Valentin Schneider , Mathieu Desnoyers , qiang.zhang@windriver.com, robdclark@chromium.org, christian@brauner.io, Dietmar Eggemann , Ingo Molnar , Juri Lelli , Vincent Guittot , Benjamin Segall , Mel Gorman , Daniel Bristot de Oliveira , David Miller , kuba@kernel.org, LKML , kernel test robot Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 13, 2021 at 9:11 PM Steven Rostedt wrote: > > On Wed, 13 Oct 2021 10:23:42 +0000 > Yafang Shao wrote: > > > kernel test robot reported a -Wstringop-truncation warning after I > > extend task comm from 16 to 24. Below is the detailed warning: > > > > fs/binfmt_elf.c: In function 'fill_psinfo.isra': > > >> fs/binfmt_elf.c:1575:9: warning: 'strncpy' output may be truncated copying 16 bytes from a string of length 23 [-Wstringop-truncation] > > 1575 | strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > This patch can fix this warning. > > > > struct elf_prpsinfo was moved from include/uapi/linux/elfcore.h into > > include/linux/elfcore.h in commit > > 1e6b57d6421f ("unexport linux/elfcore.h") > > > > As it is not UAPI code, we can replace 16 with TASK_COMM_LEN without > > worrying about breaking userspace things. > > > > struct elf_prpsinfo is used to dump the task information in userspace > > coredump or kernel vmcore. So I verified what will happen to vmcore if > > I extend the size of TASK_COMM_LEN to 24. The result is that the vmcore > > still work fine as expected, for example: > > > > crash> ps > > PID PPID CPU TASK ST %MEM VSZ RSS COMM > > > 0 0 0 ffffffff8501a940 RU 0.0 0 0 [swapper/0] > > > 0 0 1 ffff996e00f81f80 RU 0.0 0 0 [swapper/1] > > > 0 0 2 ffff996e00f80000 RU 0.0 0 0 [swapper/2] > > > 0 0 3 ffff996e00f85e80 RU 0.0 0 0 [swapper/3] > > > 0 0 4 ffff996e00f83f00 RU 0.0 0 0 [swapper/4] > > 0 0 5 ffff996e00f8de80 RU 0.0 0 0 [swapper/5] > > > 0 0 6 ffff996e00f8bf00 RU 0.0 0 0 [swapper/6] > > > 0 0 7 ffff996e00f89f80 RU 0.0 0 0 [swapper/7] > > > 0 0 8 ffff996e00f88000 RU 0.0 0 0 [swapper/8] > > > 0 0 9 ffff996e00f93f00 RU 0.0 0 0 [swapper/9] > > > 0 0 10 ffff996e00f91f80 RU 0.0 0 0 [swapper/10] > > > 0 0 11 ffff996e00f90000 RU 0.0 0 0 [swapper/11] > > > 0 0 12 ffff996e00f95e80 RU 0.0 0 0 [swapper/12] > > > 0 0 13 ffff996e00f98000 RU 0.0 0 0 [swapper/13] > > > 0 0 14 ffff996e00f9de80 RU 0.0 0 0 [swapper/14] > > > 0 0 15 ffff996e00f9bf00 RU 0.0 0 0 [swapper/15] > > > > Reported-by: kernel test robot > > Signed-off-by: Yafang Shao > > Cc: Peter Zijlstra > > Cc: Steven Rostedt > > Cc: Kees Cook > > Cc: Al Viro > > Cc: Petr Mladek > > --- > > include/linux/elfcore-compat.h | 2 +- > > include/linux/elfcore.h | 4 ++-- > > 2 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h > > index e272c3d452ce..8a52a782161d 100644 > > --- a/include/linux/elfcore-compat.h > > +++ b/include/linux/elfcore-compat.h > > @@ -43,7 +43,7 @@ struct compat_elf_prpsinfo > > __compat_uid_t pr_uid; > > __compat_gid_t pr_gid; > > compat_pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > > - char pr_fname[16]; > > + char pr_fname[TASK_COMM_LEN]; > > char pr_psargs[ELF_PRARGSZ]; > > }; > > Nice clean up, but should we add "#include " to this header, > to make sure that it pulls in TASK_COMM_LEN define and not just hope it > gets pulled in beforehand by chance? > Sure, I will add it. Thanks for the suggestion. > > > > diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h > > index 2aaa15779d50..ff4e4e455160 100644 > > --- a/include/linux/elfcore.h > > +++ b/include/linux/elfcore.h > > @@ -65,8 +65,8 @@ struct elf_prpsinfo > > __kernel_gid_t pr_gid; > > pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > > /* Lots missing */ > > - char pr_fname[16]; /* filename of executable */ > > - char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ > > + char pr_fname[TASK_COMM_LEN]; /* filename of executable */ > > + char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ > > This header is fine, as it pulls in sched/task_stack.h which includes > sched.h. > > -- Steve > > > }; > > > > static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs) > -- Thanks Yafang