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 7447AC433EF for ; Thu, 11 Nov 2021 11:47:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 597606124C for ; Thu, 11 Nov 2021 11:47:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232256AbhKKLu1 (ORCPT ); Thu, 11 Nov 2021 06:50:27 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:32089 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232570AbhKKLu0 (ORCPT ); Thu, 11 Nov 2021 06:50:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636631257; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3FPfS7kZXFceS9Lgp1RH/lsyVsBLRGLqfS3FoOXYSuE=; b=JUG0zHkr9XKE+vyp2JQ6ZOnO7o1vblP3jalWF4kINFFMYiaplaDm9Z8PxGwLW6pMoGFutK wClQirNVbisXCdAvgSvn5/0BWygrFVn7hTc6h0yMsuV02eUZe+0OWYyMOyWav098hjC4q7 vgY/hnArrBuzrOh7X+lXS0JHzwP2DMc= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-524-ZSgwm7-oNKid5VRirbY5Bw-1; Thu, 11 Nov 2021 06:47:35 -0500 X-MC-Unique: ZSgwm7-oNKid5VRirbY5Bw-1 Received: by mail-wm1-f71.google.com with SMTP id 144-20020a1c0496000000b003305ac0e03aso4653112wme.8 for ; Thu, 11 Nov 2021 03:47:35 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:organization:in-reply-to :content-transfer-encoding; bh=3FPfS7kZXFceS9Lgp1RH/lsyVsBLRGLqfS3FoOXYSuE=; b=zgSe4tsw/GkmV5+sFV/C4QFMuD3uxCYDozLEl0Hrk1oGc5BMR2WBfCe7RGsIAoVbDa HhVsOVFWS1g8c372Lt6SVXFd1AkbBCYonJSiSLRsrDPkHSn7J8XlAqsCjUvxZy7sY+p6 gSxBfLe2cB7yHAHXIiMZxcE4OAUQpqpOABdwkGPvHG3t3rPC3az5y1LaEaQnmMiLgCte tXzO0Rkvcoc18O2pu7Pyg5oH2m03nRHxjn5AQQmOZ3KcHqTut1is/JNZVCP9NRzwxjlL QFFHCwcNvegHmAARhfd6AKor0sIFpIDX4Fsx5qN7Rv9sQiswHHI4SNjGIYknPKMmGG6a Iayg== X-Gm-Message-State: AOAM531HB2CvVAJVMYX4NTBtxoyu+b6iKnIdiBLjngK3uRz4Z1M9LhEq 7Zoo6MZIGYxOsrszeegiYvcFoI+dn4qkJAhoHLRzDoO7e0A7emjRDnKMy7cSsdbQCJxcxSGUJBc 0MAKCEH6l09Re0+AKzouOJ2RoqA== X-Received: by 2002:a5d:45cc:: with SMTP id b12mr8082380wrs.164.1636631254684; Thu, 11 Nov 2021 03:47:34 -0800 (PST) X-Google-Smtp-Source: ABdhPJwO566pckJvXEcwz+OG93YPsApF+toGZKExvaMFLBrnliRRTv/LgjAiYUOFAAaeaDr4bLvTMw== X-Received: by 2002:a5d:45cc:: with SMTP id b12mr8082352wrs.164.1636631254480; Thu, 11 Nov 2021 03:47:34 -0800 (PST) Received: from [192.168.3.132] (p4ff23ee8.dip0.t-ipconnect.de. [79.242.62.232]) by smtp.gmail.com with ESMTPSA id d8sm2782565wrm.76.2021.11.11.03.47.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Nov 2021 03:47:33 -0800 (PST) Message-ID: <70dd5e1c-99c9-c1ca-4e3f-1a894896cf06@redhat.com> Date: Thu, 11 Nov 2021 12:47:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH 4/7] fs/binfmt_elf: use get_task_comm instead of open-coded string copy Content-Language: en-US To: Petr Mladek Cc: Yafang Shao , akpm@linux-foundation.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, oliver.sang@intel.com, lkp@intel.com, Kees Cook , Mathieu Desnoyers , Arnaldo Carvalho de Melo , Andrii Nakryiko , Michal Miroslaw , Peter Zijlstra , Steven Rostedt , Matthew Wilcox , Al Viro References: <20211108083840.4627-1-laoar.shao@gmail.com> <20211108083840.4627-5-laoar.shao@gmail.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 11.11.21 12:34, Petr Mladek wrote: > On Thu 2021-11-11 11:06:04, David Hildenbrand wrote: >> On 11.11.21 11:03, David Hildenbrand wrote: >>> On 08.11.21 09:38, Yafang Shao wrote: >>>> It is better to use get_task_comm() instead of the open coded string >>>> copy as we do in other places. >>>> >>>> struct elf_prpsinfo is used to dump the task information in userspace >>>> coredump or kernel vmcore. Below is the verfication of vmcore, >>>> >>>> crash> ps >>>> PID PPID CPU TASK ST %MEM VSZ RSS COMM >>>> 0 0 0 ffffffff9d21a940 RU 0.0 0 0 [swapper/0] >>>>> 0 0 1 ffffa09e40f85e80 RU 0.0 0 0 [swapper/1] >>>>> 0 0 2 ffffa09e40f81f80 RU 0.0 0 0 [swapper/2] >>>>> 0 0 3 ffffa09e40f83f00 RU 0.0 0 0 [swapper/3] >>>>> 0 0 4 ffffa09e40f80000 RU 0.0 0 0 [swapper/4] >>>>> 0 0 5 ffffa09e40f89f80 RU 0.0 0 0 [swapper/5] >>>> 0 0 6 ffffa09e40f8bf00 RU 0.0 0 0 [swapper/6] >>>>> 0 0 7 ffffa09e40f88000 RU 0.0 0 0 [swapper/7] >>>>> 0 0 8 ffffa09e40f8de80 RU 0.0 0 0 [swapper/8] >>>>> 0 0 9 ffffa09e40f95e80 RU 0.0 0 0 [swapper/9] >>>>> 0 0 10 ffffa09e40f91f80 RU 0.0 0 0 [swapper/10] >>>>> 0 0 11 ffffa09e40f93f00 RU 0.0 0 0 [swapper/11] >>>>> 0 0 12 ffffa09e40f90000 RU 0.0 0 0 [swapper/12] >>>>> 0 0 13 ffffa09e40f9bf00 RU 0.0 0 0 [swapper/13] >>>>> 0 0 14 ffffa09e40f98000 RU 0.0 0 0 [swapper/14] >>>>> 0 0 15 ffffa09e40f9de80 RU 0.0 0 0 [swapper/15] >>>> >>>> It works well as expected. >>>> >>>> Suggested-by: Kees Cook >>>> Signed-off-by: Yafang Shao >>>> Cc: Mathieu Desnoyers >>>> Cc: Arnaldo Carvalho de Melo >>>> Cc: Andrii Nakryiko >>>> Cc: Michal Miroslaw >>>> Cc: Peter Zijlstra >>>> Cc: Steven Rostedt >>>> Cc: Matthew Wilcox >>>> Cc: David Hildenbrand >>>> Cc: Al Viro >>>> Cc: Kees Cook >>>> Cc: Petr Mladek >>>> --- >>>> fs/binfmt_elf.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c >>>> index a813b70f594e..138956fd4a88 100644 >>>> --- a/fs/binfmt_elf.c >>>> +++ b/fs/binfmt_elf.c >>>> @@ -1572,7 +1572,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, >>>> SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid)); >>>> SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid)); >>>> rcu_read_unlock(); >>>> - strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); >>>> + get_task_comm(psinfo->pr_fname, p); >>>> >>>> return 0; >>>> } >>>> >>> >>> We have a hard-coded "pr_fname[16]" as well, not sure if we want to >>> adjust that to use TASK_COMM_LEN? >> >> But if the intention is to chance TASK_COMM_LEN later, we might want to >> keep that unchanged. > > It seems that len will not change in the end. Another solution is > going to be used for the long names, see > https://lore.kernel.org/r/20211108084142.4692-1-laoar.shao@gmail.com. Yes, that's what I recall as well. The I read the patch subjects+descriptions in this series "make it adopt to task comm size change" and was slightly confused. Maybe we should just remove any notion of "task comm size change" from this series and instead just call it a cleanup. -- Thanks, David / dhildenb