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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 D2AEEC433E2 for ; Tue, 30 Mar 2021 09:43:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CADA619AE for ; Tue, 30 Mar 2021 09:43:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230303AbhC3JnP (ORCPT ); Tue, 30 Mar 2021 05:43:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231519AbhC3JnB (ORCPT ); Tue, 30 Mar 2021 05:43:01 -0400 Received: from smtp-190e.mail.infomaniak.ch (smtp-190e.mail.infomaniak.ch [IPv6:2001:1600:4:17::190e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1C38C061574; Tue, 30 Mar 2021 02:43:01 -0700 (PDT) Received: from smtp-3-0001.mail.infomaniak.ch (unknown [10.4.36.108]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4F8kyW6mfzzMpvrk; Tue, 30 Mar 2021 11:42:59 +0200 (CEST) Received: from ns3096276.ip-94-23-54.eu (unknown [23.97.221.149]) by smtp-3-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4F8kyV6y72zlh8TT; Tue, 30 Mar 2021 11:42:58 +0200 (CEST) Subject: Re: [PATCH v1] ovl: Fix leaked dentry To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, Amir Goldstein , Vivek Goyal , stable@vger.kernel.org, syzbot , =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= References: <20210329164907.2133175-1-mic@digikod.net> From: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= Message-ID: Date: Tue, 30 Mar 2021 11:44:00 +0200 User-Agent: MIME-Version: 1.0 In-Reply-To: <20210329164907.2133175-1-mic@digikod.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On 29/03/2021 18:49, Mickaël Salaün wrote: > From: Mickaël Salaün > > Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in > ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a > metacopy error, which leads to dentry leaks when shutting down the > related superblock: > > overlayfs: refusing to follow metacopy origin for (/file0) > ... > BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] > ... > WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d > CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 > ... > RIP: 0010:umount_check.cold+0x107/0x14d > ... > Call Trace: > d_walk+0x28c/0x950 > ? dentry_lru_isolate+0x2b0/0x2b0 > ? __kasan_slab_free+0x12/0x20 > do_one_tree+0x33/0x60 > shrink_dcache_for_umount+0x78/0x1d0 > generic_shutdown_super+0x70/0x440 > kill_anon_super+0x3e/0x70 > deactivate_locked_super+0xc4/0x160 > deactivate_super+0xfa/0x140 > cleanup_mnt+0x22e/0x370 > __cleanup_mnt+0x1a/0x30 > task_work_run+0x139/0x210 > do_exit+0xb0c/0x2820 > ? __kasan_check_read+0x1d/0x30 > ? find_held_lock+0x35/0x160 > ? lock_release+0x1b6/0x660 > ? mm_update_next_owner+0xa20/0xa20 > ? reacquire_held_locks+0x3f0/0x3f0 > ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 > do_group_exit+0x135/0x380 > __do_sys_exit_group.isra.0+0x20/0x20 > __x64_sys_exit_group+0x3c/0x50 > do_syscall_64+0x45/0x70 > entry_SYSCALL_64_after_hwframe+0x44/0xae > ... > VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day... > > This fix has been tested with a syzkaller reproducer. > > Cc: Amir Goldstein > Cc: Miklos Szeredi > Cc: Vivek Goyal > Cc: # v5.7+ The bogus commit 6815f479ca90 was applied on v5.7-rc2 but it is only available since v5.8+ . > Reported-by: syzbot > Fixes: 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()") > Signed-off-by: Mickaël Salaün > Link: https://lore.kernel.org/r/20210329164907.2133175-1-mic@digikod.net > --- > fs/overlayfs/namei.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c > index 3fe05fb5d145..424c594afd79 100644 > --- a/fs/overlayfs/namei.c > +++ b/fs/overlayfs/namei.c > @@ -921,6 +921,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, > if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { > err = -EPERM; > pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry); > + dput(this); > goto out_put; > } > > > base-commit: a5e13c6df0e41702d2b2c77c8ad41677ebb065b3 >