[PATCH 6.1.96] gfs2: Fix slab-use-after-free in gfs2_qd_dealloc

[Clayton Casciato <majortomtosourcecontrol@gmail.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In gfs2_put_super(), whether withdrawn or not, the quota should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.

The origin of a cherry-pick conflict is the (relevant) code block added in
commit f66af88e3321 ("gfs2: Stop using gfs2_make_fs_ro for withdraw")

There are no references to gfs2_withdrawn() nor gfs2_destroy_threads() in
gfs2_put_super(), so we can simply call gfs2_quota_cleanup() in a new else
block as bdcb8aa434c6 achieves.

Else braces were used for consistency with the if block.

Sponsor: 21SoftWare LLC
Signed-off-by: Clayton Casciato <majortomtosourcecontrol@gmail.com>
---
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 302d1e43d701..6107cd680176 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -591,6 +591,8 @@ static void gfs2_put_super(struct super_block *sb)
 
 	if (!sb_rdonly(sb)) {
 		gfs2_make_fs_ro(sdp);
+	} else {
+		gfs2_quota_cleanup(sdp);
 	}
 	WARN_ON(gfs2_withdrawing(sdp));