builtin/submodule--helper: fix leaking remote ref on errors

When `update_submodule()` fails we return with `die_message()`, which
only causes us to print the same message as `die()` would without
actually causing the process to die. We don't free memory in that case
and thus leak memory.

Fix the leak by freeing the remote ref.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

builtin/submodule--helper.c

@@ -2648,15 +2648,20 @@ static int update_submodule(struct update_data *update_data)
 
 		if (!update_data->nofetch) {
 			if (fetch_in_submodule(update_data->sm_path, update_data->depth,
-					      0, NULL))
+					      0, NULL)) {
+				free(remote_ref);
 				return die_message(_("Unable to fetch in submodule path '%s'"),
 						   update_data->sm_path);
+			}
 		}
 
 		if (repo_resolve_gitlink_ref(the_repository, update_data->sm_path,
-					     remote_ref, &update_data->oid))
-			return die_message(_("Unable to find %s revision in submodule path '%s'"),
-					   remote_ref, update_data->sm_path);
+					     remote_ref, &update_data->oid)) {
+			ret = die_message(_("Unable to find %s revision in submodule path '%s'"),
+					  remote_ref, update_data->sm_path);
+			free(remote_ref);
+			return ret;
+		}
 
 		free(remote_ref);
 	}

t/t7420-submodule-set-url.sh

@@ -10,6 +10,7 @@ as expected.
 '
 
 TEST_NO_CREATE_REPO=1
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '