From 1fb254aa983bf190cfd685d40c64a480a9bafaee Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Thu, 22 Aug 2019 20:55:54 -0700
Subject: [PATCH] xfs: fix missing ILOCK unlock when xfs_setattr_nonsize fails
 due to EDQUOT
Git-commit: 1fb254aa983bf190cfd685d40c64a480a9bafaee
Patch-mainline: v5.3-rc6
References: bsc#1148032, bsc#1148093, CVE-2019-15538

Benjamin Moody reported to Debian that XFS partially wedges when a chgrp
fails on account of being out of disk quota.  I ran his reproducer
Script: 

# adduser dummy
# adduser dummy plugdev

# dd if=/dev/zero bs=1M count=100 of=test.img
# mkfs.xfs test.img
# mount -t xfs -o gquota test.img /mnt
# mkdir -p /mnt/dummy
# chown -c dummy /mnt/dummy
# xfs_quota -xc 'limit -g bsoft=100k bhard=100k plugdev' /mnt

(and then as user dummy)

$ dd if=/dev/urandom bs=1M count=50 of=/mnt/dummy/foo
$ chgrp plugdev /mnt/dummy/foo

and saw:

================================================
Warning: lock held when returning to user space!
5.3.0-rc5 #rc5 Tainted: G        W

Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>

------------------------------------------------
chgrp/47006 is leaving the kernel with locks still held!
1 lock held by chgrp/47006:
 #0: 000000006664ea2d (&xfs_nondir_ilock_class){++++}, at: xfs_ilock+0xd2/0x290 [xfs]

...which is clearly caused by xfs_setattr_nonsize failing to unlock the
ILOCK after the xfs_qm_vop_chown_reserve call fails.  Add the missing
unlock.

Reported-by: benjamin.moody@gmail.com
Fixes: 253f4911f297 ("xfs: better xfs_trans_alloc interface")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
---
 fs/xfs/xfs_iops.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index ff3c1fae5357..fe285d123d69 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -793,6 +793,7 @@ xfs_setattr_nonsize(
 
 out_cancel:
 	xfs_trans_cancel(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 out_dqrele:
 	xfs_qm_dqrele(udqp);
 	xfs_qm_dqrele(gdqp);
-- 
2.16.4