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 X-Spam-Level: X-Spam-Status: No, score=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40D65C433DB for ; Tue, 9 Mar 2021 19:05:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07B1865230 for ; Tue, 9 Mar 2021 19:05:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231265AbhCITFS (ORCPT ); Tue, 9 Mar 2021 14:05:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230288AbhCITFP (ORCPT ); Tue, 9 Mar 2021 14:05:15 -0500 Received: from mail-ej1-x62c.google.com (mail-ej1-x62c.google.com [IPv6:2a00:1450:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B597C06174A; Tue, 9 Mar 2021 11:05:15 -0800 (PST) Received: by mail-ej1-x62c.google.com with SMTP id dx17so30776935ejb.2; Tue, 09 Mar 2021 11:05:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=3B1rfVT/1MapX7VMCgOxa4XmZopN8HbNzmnG/7rsfgQ=; b=UHCRXggSJfUa2CgVkSB7dL/4Y5FXhX0eaFb5Av4/n6K6BgIC0i/eubDi5wkFBKAWCW 3O3YKzjk7lvVkzJWYm0PodTCGxgXZmkeSqxOhRVoWk8/FsbKyu7ycbCBQQ9zdq/sy+UW juHXYFWckJ9tOZPOiy1eSEIXU54wAZTP7VVeFfUbz2NJzeJc5ZtlYPKZ7oChO50opBPF V9lTHgovzzjbjNGBCT9qsWb4Kz3RgnJHqqqk8JTwIDl0Q1JzoJR+SpEcZBWNPE1Vaf+0 eVCvQY78DUn+WVmXMKzUrmzIz55wbfO7sreNpud0MfyjvTe5tr+F+wdyLphhN05RS/k7 p3/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=3B1rfVT/1MapX7VMCgOxa4XmZopN8HbNzmnG/7rsfgQ=; b=dqhoIKyR8Nw3K/FHiDIVO4mcPDIO0nHihNdbBEp2LfS2myLG9dkqx6SJ8fQg4WlcM6 +ccbr1uOgKcB0JLYM+XFFD+e2b0k28VVUAVBm9xKmlikZy70Y4stYPu/N8E3fAbP4p84 4VUD27DMEszl2Mv0mZegjpShTuWARA39sLXN3kkMn3r7djtxut7/bx2smr5Cy7AUbUII iglM8SKqIfrk0svphuwiwuWITUeMmRX8Lqwn81Tq9N3WVZIh0Xw3co2h0YpVCDgCGvMu L55u7KgRyXMZXxuZTdkX3W/JcwMZA5geSkuhD4fMK5mvxdpmLOw32nlWg3zYH7MeXeNW EaZQ== X-Gm-Message-State: AOAM531tifq8bCqghUiIhJ95HcSJpILBqbgaI0jJP/w4oKJ1zMuKaztW 6H71xbamshFbCdHt0gNZgA== X-Google-Smtp-Source: ABdhPJwK8G/3vajvhyL3Z6b2MUVjPIAuxx8+/N6Is3CGCXaZnJztCDcTnqTZcFLBs1EZ53Jb0WgwEQ== X-Received: by 2002:a17:907:aa2:: with SMTP id bz2mr22247785ejc.239.1615316714077; Tue, 09 Mar 2021 11:05:14 -0800 (PST) Received: from localhost.localdomain ([46.53.252.54]) by smtp.gmail.com with ESMTPSA id a22sm9046312ejr.89.2021.03.09.11.05.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Mar 2021 11:05:13 -0800 (PST) Date: Tue, 9 Mar 2021 22:05:11 +0300 From: Alexey Dobriyan To: Eric Biggers Cc: Jia-Ju Bai , christian@brauner.io, ebiederm@xmission.com, akpm@linux-foundation.org, keescook@chromium.org, gladkov.alexey@gmail.com, walken@google.com, bernd.edlinger@hotmail.de, avagin@gmail.com, deller@gmx.de, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] fs: proc: fix error return code of proc_map_files_readdir() Message-ID: References: <20210309095527.27969-1-baijiaju1990@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 09, 2021 at 10:30:23AM -0800, Eric Biggers wrote: > On Tue, Mar 09, 2021 at 01:55:27AM -0800, Jia-Ju Bai wrote: > > When get_task_mm() returns NULL to mm, no error return code of > > proc_map_files_readdir() is assigned. > > To fix this bug, ret is assigned with -ENOENT in this case. > > --- a/fs/proc/base.c > > +++ b/fs/proc/base.c > > @@ -2332,8 +2332,10 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) > > goto out_put_task; > > > > mm = get_task_mm(task); > > - if (!mm) > > + if (!mm) { > > + ret = -ENOENT; > > goto out_put_task; > > + } > > > > ret = mmap_read_lock_killable(mm); > > Is there something in particular that makes you think that returning ENOENT is > the correct behavior in this case? Try 'ls /proc/$pid/map_files' where pid is a > kernel thread; it's an empty directory, which is probably intentional. Your > patch would change reading the directory to fail with ENOENT. Yes. 0 from readdir means "no more stuff", not an error.