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=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 0F880ECE599 for ; Wed, 16 Oct 2019 22:14:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC8D121925 for ; Wed, 16 Oct 2019 22:14:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571264075; bh=+Xx8dEvgQfqrBHSIOX0sGjnhqv4hoRx4grH9nfmkAtg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U0R3VU3NnSxtI0uomsmeno0NiUYK+kTIHFj9R93EVpUlpxRMGqFpqj5YaFCgtNmQv xcYIDpfjFYC5L+MQRAK8T7sedlUDnBt49DBBdHvD9AmKmBI/jdYJbnDq4kp8UVuG0y imoMU9ibL8wpKKLA5k7JItxSkuxHHqtaJ7xbUxIk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395294AbfJPVzk (ORCPT ); Wed, 16 Oct 2019 17:55:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:46376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395252AbfJPVzd (ORCPT ); Wed, 16 Oct 2019 17:55:33 -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 9ABBA21D7F; Wed, 16 Oct 2019 21:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571262932; bh=+Xx8dEvgQfqrBHSIOX0sGjnhqv4hoRx4grH9nfmkAtg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aIIpjv+fGVWGMJRJ7NLrZloPPGEAQZfDEO1HeEw2/Xm7uaIXi7yW87Hfg296YDzPq VTjYALCcJ0spv5GOexF1EbbSyIV3sn/Xedl7PYcsoQt92QrABhsTE9WTNTU/VOVnoU QcreUb7kXbVWH+3p7qniuNhK7mIbs/Y08bBdUqBI= 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 4.9 92/92] xfs: clear sb->s_fs_info on mount failure Date: Wed, 16 Oct 2019 14:51:05 -0700 Message-Id: <20191016214849.217245343@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016214759.600329427@linuxfoundation.org> References: <20191016214759.600329427@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 @@ -1674,6 +1674,7 @@ 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: @@ -1691,6 +1692,10 @@ 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); @@ -1700,6 +1705,8 @@ 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); } @@ -1719,6 +1726,9 @@ 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)); }