[PATCH v3] ceph: avoid putting the realm twice when decoding snaps fails

[xiubli@redhat.com]

From: Xiubo Li <xiubli@redhat.com>

When decoding the snaps fails it maybe leaving the 'first_realm'
and 'realm' pointing to the same snaprealm memory. And then it'll
put it twice and could cause random use-after-free, BUG_ON, etc
issues.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/57686
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/ceph/snap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 9bceed2ebda3..f5b0fa1ff705 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -775,6 +775,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 
 	dout("%s deletion=%d\n", __func__, deletion);
 more:
+	realm = NULL;
 	rebuild_snapcs = 0;
 	ceph_decode_need(&p, e, sizeof(*ri), bad);
 	ri = p;
-- 
2.31.1