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Subject[PATCH AUTOSEL 6.6 11/11] gfs2: Fix slab-use-after-free in gfs2_qd_dealloc
Date
From: Juntong Deng <juntong.deng@outlook.com>

[ Upstream commit bdcb8aa434c6d36b5c215d02a9ef07551be25a37 ]

In gfs2_put_super(), whether withdrawn or not, the quota should
be cleaned up by gfs2_quota_cleanup().

Otherwise, struct gfs2_sbd will be freed before gfs2_qd_dealloc (rcu
callback) has run for all gfs2_quota_data objects, resulting in
use-after-free.

Also, gfs2_destroy_threads() and gfs2_quota_cleanup() is already called
by gfs2_make_fs_ro(), so in gfs2_put_super(), after calling
gfs2_make_fs_ro(), there is no need to call them again.

Reported-by: syzbot+29c47e9e51895928698c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=29c47e9e51895928698c
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/super.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 0dd5641990b90..5f4ebe279aaae 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -602,13 +602,15 @@ static void gfs2_put_super(struct super_block *sb)
}
spin_unlock(&sdp->sd_jindex_spin);

- if (!sb_rdonly(sb)) {
+ if (!sb_rdonly(sb))
gfs2_make_fs_ro(sdp);
- }
- if (gfs2_withdrawn(sdp)) {
- gfs2_destroy_threads(sdp);
+ else {
+ if (gfs2_withdrawn(sdp))
+ gfs2_destroy_threads(sdp);
+
gfs2_quota_cleanup(sdp);
}
+
WARN_ON(gfs2_withdrawing(sdp));

/* At this point, we're through modifying the disk */
--
2.42.0
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