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 ---
Changed in V4: - remove initilizing of 'realm'.
fs/ceph/snap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 9bceed2ebda3..c1c452afa84d 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -764,7 +764,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc, struct ceph_mds_snap_realm *ri; /* encoded */ __le64 *snaps; /* encoded */ __le64 *prior_parent_snaps; /* encoded */ - struct ceph_snap_realm *realm = NULL; + struct ceph_snap_realm *realm; struct ceph_snap_realm *first_realm = NULL; struct ceph_snap_realm *realm_to_rebuild = NULL; int rebuild_snapcs; @@ -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;