ceph: fix memory leaks in ceph_mdsc_build_path()

Add __putname() calls to error code paths that did not free the "path"
pointer obtained by __getname().  If ownership of this pointer is not
passed to the caller via path_info.path, the function must free it
before returning.

Cc: stable@vger.kernel.org
Fixes: 3fd945a79e ("ceph: encode encrypted name in ceph_mdsc_build_path and dentry release")
Fixes: 550f7ca98e ("ceph: give up on paths longer than PATH_MAX")
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -2768,6 +2768,7 @@ retry:
 			if (ret < 0) {
 				dput(parent);
 				dput(cur);
+				__putname(path);
 				return ERR_PTR(ret);
 			}
 
@@ -2777,6 +2778,7 @@ retry:
 				if (len < 0) {
 					dput(parent);
 					dput(cur);
+					__putname(path);
 					return ERR_PTR(len);
 				}
 			}
@@ -2813,6 +2815,7 @@ retry:
 		 * cannot ever succeed.  Creating paths that long is
 		 * possible with Ceph, but Linux cannot use them.
 		 */
+		__putname(path);
 		return ERR_PTR(-ENAMETOOLONG);
 	}