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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 8FDAAECE599 for ; Wed, 16 Oct 2019 21:54:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67D6321D7A for ; Wed, 16 Oct 2019 21:54:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262845; bh=0pRgjxjxcQutTSf8K2BeQpWt/9VHQ1dqxNGgKWkcSAg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mgwC2qxJrnjvCbzihith4W9RYdMxJjanVETne7n3YgsFeY+geY7cg2OKcYDo/RiAh 7uSQnIqmIzp7J9yFh99BfxErKLw7PSrSQ9sYsh71zZof2QqZzDDzUjttjXBV3GFbZ2 MWo7kUXFhSCdB40vSHuWZHQ7dO/JahTo7w/Sw3Dg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437662AbfJPVyE (ORCPT ); Wed, 16 Oct 2019 17:54:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:43378 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394931AbfJPVx5 (ORCPT ); Wed, 16 Oct 2019 17:53:57 -0400 Received: from localhost (unknown [192.55.54.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 11CF821925; Wed, 16 Oct 2019 21:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262837; bh=0pRgjxjxcQutTSf8K2BeQpWt/9VHQ1dqxNGgKWkcSAg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NSWR96jlQyJm2h6JnIy0YEj0+PuelceXGt5K3Y1YUVwWBfiWpHNL0JcEGIqCVM9RP CNocMGsNBTh8YaUydBNvDB8ANfblYHoWIvQ4SkqtdbFbCBo9oqwt3dB/ExM4AksIjV 92S5EnY+lwhkwm3HggTEmBdqtrmfMqLlFM9aJFP4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Chinner , "Darrick J. Wong" , Ajay Kaher Subject: [PATCH 4.4 79/79] xfs: clear sb->s_fs_info on mount failure Date: Wed, 16 Oct 2019 14:50:54 -0700 Message-Id: <20191016214834.705602853@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016214729.758892904@linuxfoundation.org> References: <20191016214729.758892904@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Chinner commit c9fbd7bbc23dbdd73364be4d045e5d3612cf6e82 upstream. We recently had an oops reported on a 4.14 kernel in xfs_reclaim_inodes_count() where sb->s_fs_info pointed to garbage and so the m_perag_tree lookup walked into lala land. Essentially, the machine was under memory pressure when the mount was being run, xfs_fs_fill_super() failed after allocating the xfs_mount and attaching it to sb->s_fs_info. It then cleaned up and freed the xfs_mount, but the sb->s_fs_info field still pointed to the freed memory. Hence when the superblock shrinker then ran it fell off the bad pointer. With the superblock shrinker problem fixed at teh VFS level, this stale s_fs_info pointer is still a problem - we use it unconditionally in ->put_super when the superblock is being torn down, and hence we can still trip over it after a ->fill_super call failure. Hence we need to clear s_fs_info if xfs-fs_fill_super() fails, and we need to check if it's valid in the places it can potentially be dereferenced after a ->fill_super failure. Signed-Off-By: Dave Chinner Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Ajay Kaher Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_super.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1572,6 +1572,7 @@ xfs_fs_fill_super( out_close_devices: xfs_close_devices(mp); out_free_fsname: + sb->s_fs_info = NULL; xfs_free_fsname(mp); kfree(mp); out: @@ -1589,6 +1590,10 @@ xfs_fs_put_super( { struct xfs_mount *mp = XFS_M(sb); + /* if ->fill_super failed, we have no mount to tear down */ + if (!sb->s_fs_info) + return; + xfs_notice(mp, "Unmounting Filesystem"); xfs_filestream_unmount(mp); xfs_unmountfs(mp); @@ -1598,6 +1603,8 @@ xfs_fs_put_super( xfs_destroy_percpu_counters(mp); xfs_destroy_mount_workqueues(mp); xfs_close_devices(mp); + + sb->s_fs_info = NULL; xfs_free_fsname(mp); kfree(mp); } @@ -1617,6 +1624,9 @@ xfs_fs_nr_cached_objects( struct super_block *sb, struct shrink_control *sc) { + /* Paranoia: catch incorrect calls during mount setup or teardown */ + if (WARN_ON_ONCE(!sb->s_fs_info)) + return 0; return xfs_reclaim_inodes_count(XFS_M(sb)); }