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 54DB8C433FE for ; Tue, 26 Oct 2021 01:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 380C861074 for ; Tue, 26 Oct 2021 01:51:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232987AbhJZBxn (ORCPT ); Mon, 25 Oct 2021 21:53:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231971AbhJZBxm (ORCPT ); Mon, 25 Oct 2021 21:53:42 -0400 Received: from mail-io1-xd36.google.com (mail-io1-xd36.google.com [IPv6:2607:f8b0:4864:20::d36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1E94C061745; Mon, 25 Oct 2021 18:51:19 -0700 (PDT) Received: by mail-io1-xd36.google.com with SMTP id o184so18129230iof.6; Mon, 25 Oct 2021 18:51:19 -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=M+TEaQB1KaSOudASCPt2E3PS4ymJyoJAqUYafZ8gI7E=; b=oL8HHOwwrFG5e/LmuN4agIcEJfacHoUr4ai/CCnAQSW/UKvac/ju9Spl9S9IctkdMV u0xR2bACpUqrjpo/d3B+q1N6PyNK5ARQbG4fte2a2ZeidUraP8oLilSHNXEM9gU0CM+I SbO2q5cPvNWPOqMrm+ujryeD7OZDrL2sot8WITIksRGltQ4ED6m5RR4JvhnniPEr0cIJ 1JuVaVB6Rv7gWKPXWYUWuUxracYP9X5Yyy77zUMhI1TK6oK1YwDlTQ+j3ASsLa/eokld MkDGJwXZSGj2b87w6vxWYa8EEp7aHhVpWjIf4Q3+7yIsWlT4MlYFozO9j7Xg4hpf4VFu u+jw== 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=M+TEaQB1KaSOudASCPt2E3PS4ymJyoJAqUYafZ8gI7E=; b=qfJnDPw8lTYjHE8ocNM48qavwlU/an4GeU2JrC8jppYMH0eSV9jsJ5tOy5puLTrhBc StaW2nJoDs2GVMEeFbQfz8B+7gUNQXd44FcA4gq6DUh7zQHA/bd2pAu7zjOpyITPeAzQ YGPMdxNfxlw66Q100l8glUhizE+I0zGbazaLkFgwsVUGMhMSY21TxZrG+Wj8LndkDdmY SaVmIcVhI3pxe8IYciO9FO2ixEK3xultBy6w+BDsK4y5hkCDOAhA1kbFSXZMBe+rVP+X mfAljVJGJ6NGcgJjNC6L7ckBI/gu1/OXeBIsrWQaRu5/vBKvK7LbLp870yzbrTqxtO4s 6FEg== X-Gm-Message-State: AOAM530a+IWBGYvHyKT5d5FPDnn5LIOXt6EwDwWzait7qB1l0ui4xsJx 5z0Vsh2Qs/Hkq7i90P9askt6bevqr/v3Jd7spwo= X-Google-Smtp-Source: ABdhPJzo8Pl2UbPecXV9ZclgT3FzrihDFm7Isxsh4OePzHurnJ+maCBZCvaVaerHAt6wvuSmpFvZzPlkXSA+3EMqRwA= X-Received: by 2002:a5d:9493:: with SMTP id v19mr13031702ioj.34.1635213079114; Mon, 25 Oct 2021 18:51:19 -0700 (PDT) MIME-Version: 1.0 References: <20211025083315.4752-1-laoar.shao@gmail.com> <20211025083315.4752-4-laoar.shao@gmail.com> <202110251411.93B477676B@keescook> In-Reply-To: <202110251411.93B477676B@keescook> From: Yafang Shao Date: Tue, 26 Oct 2021 09:50:43 +0800 Message-ID: Subject: Re: [PATCH v6 03/12] drivers/connector: make connector comm always nul ternimated To: Kees Cook Cc: Andrew Morton , Steven Rostedt , Mathieu Desnoyers , Arnaldo Carvalho de Melo , Petr Mladek , Peter Zijlstra , Al Viro , Valentin Schneider , Qiang Zhang , robdclark , christian , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Vincent Guittot , David Miller , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin Lau , Song Liu , Yonghong Song , john fastabend , KP Singh , dennis.dalessandro@cornelisnetworks.com, mike.marciniszyn@cornelisnetworks.com, dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, netdev , bpf , "linux-perf-use." , linux-fsdevel@vger.kernel.org, Linux MM , LKML , kernel test robot , kbuild test robot , Andrii Nakryiko , Vladimir Zapolskiy , David Howells Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Oct 26, 2021 at 5:14 AM Kees Cook wrote: > > On Mon, Oct 25, 2021 at 08:33:06AM +0000, Yafang Shao wrote: > > connector comm was introduced in commit > > f786ecba4158 ("connector: add comm change event report to proc connector"). > > struct comm_proc_event was defined in include/linux/cn_proc.h first and > > then been moved into file include/uapi/linux/cn_proc.h in commit > > 607ca46e97a1 ("UAPI: (Scripted) Disintegrate include/linux"). > > > > As this is the UAPI code, we can't change it without potentially breaking > > things (i.e. userspace binaries have this size built in, so we can't just > > change the size). To prepare for the followup change - extending task > > comm, we have to use __get_task_comm() to avoid the BUILD_BUG_ON() in > > proc_comm_connector(). > > I wonder, looking at this again, if it might make more sense to avoid > this cn_proc.c change, and instead, adjust get_task_comm() like so: > > #define get_task_comm(buf, tsk) > __get_task_comm(buf, __must_be_array(buf) + sizeof(buf), tsk) > > This would still enforce the original goal of making sure > get_task_comm() is being used on a char array, and now that > __get_task_comm() will truncate & pad, it's safe to use on both > too-small and too-big arrays. > It Makes sense to me. I will do it as you suggested. -- Thanks Yafang