cifs: fix leak in FSCTL_ENUM_SNAPS response handling

The server may respond with success, and an output buffer less than
sizeof(struct smb_snapshot_array) in length. Do not leak the output
buffer in this case.

Fixes: 834170c85978 ("Enable previous version support")
Signed-off-by: David Disseldorp <ddiss@suse.de>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 152e37f..c586918 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -942,6 +942,7 @@
 		}
 		if (snapshot_in.snapshot_array_size < sizeof(struct smb_snapshot_array)) {
 			rc = -ERANGE;
+			kfree(retbuf);
 			return rc;
 		}