gfs2: Fix slab-use-after-free in gfs2_qd_dealloc

commit bdcb8aa434c6d36b5c215d02a9ef07551be25a37 upstream.

In gfs2_put_super(), whether withdrawn or not, the quota should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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Clayton Casciato <majortomtosourcecontrol@gmail.com>

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 302d1e43d701206325d55908b7c0e5a272171493..6107cd680176c010a6aca699214b63f11a2fcd28 100644 (file)
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -591,6 +591,8 @@ restart:
 
        if (!sb_rdonly(sb)) {
                gfs2_make_fs_ro(sdp);
+       } else {
+               gfs2_quota_cleanup(sdp);
        }
        WARN_ON(gfs2_withdrawing(sdp));