From: Xiubo Li <xiubli@xxxxxxxxxx> commit 51884d153f7ec85e18d607b2467820a90e0f4359 upstream. 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@xxxxxxxxxxxxxxx Link: https://tracker.ceph.com/issues/57686 Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx> Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ceph/snap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -763,7 +763,7 @@ int ceph_update_snap_trace(struct ceph_m 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; @@ -774,6 +774,7 @@ int ceph_update_snap_trace(struct ceph_m dout("%s deletion=%d\n", __func__, deletion); more: + realm = NULL; rebuild_snapcs = 0; ceph_decode_need(&p, e, sizeof(*ri), bad); ri = p;
