ceph: fix cred leak in ceph_mds_check_access()

commit c5cf420303256dcd6ff175643e9e9558543c2047 upstream.

get_current_cred() increments the reference counter, but the
put_cred() call was missing.

Cc: stable@vger.kernel.org
Fixes: 596afb0b89 ("ceph: add ceph_mds_check_access() helper")
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ceph/mds_client.c

@@ -5736,6 +5736,7 @@ int ceph_mds_check_access(struct ceph_mds_client *mdsc, char *tpath, int mask)
 
 		err = ceph_mds_auth_match(mdsc, s, cred, tpath);
 		if (err < 0) {
+			put_cred(cred);
 			return err;
 		} else if (err > 0) {
 			/* always follow the last auth caps' permision */
@@ -5751,6 +5752,8 @@ int ceph_mds_check_access(struct ceph_mds_client *mdsc, char *tpath, int mask)
 		}
 	}
 
+	put_cred(cred);
+
 	doutc(cl, "root_squash_perms %d, rw_perms_s %p\n", root_squash_perms,
 	      rw_perms_s);
 	if (root_squash_perms && rw_perms_s == NULL) {