upload-pack: fix leaking child process data on reachability checks

We spawn a git-rev-list(1) command to perform reachability checks in
"upload-pack.c". We do not release memory associated with the process
in error cases though, thus leaking memory.

Fix these by calling `child_process_clear()`.

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

Author: pks-t

t/t5516-fetch-push.sh

@@ -19,6 +19,7 @@ GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 TEST_CREATE_REPO_NO_TEMPLATE=1
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 D=$(pwd)

upload-pack.c

@@ -709,10 +709,13 @@ static int get_reachable_list(struct upload_pack_data *data,
 	struct object *o;
 	char namebuf[GIT_MAX_HEXSZ + 2]; /* ^ + hash + LF */
 	const unsigned hexsz = the_hash_algo->hexsz;
+	int ret;
 
 	if (do_reachable_revlist(&cmd, &data->shallows, reachable,
-				 data->allow_uor) < 0)
-		return -1;
+				 data->allow_uor) < 0) {
+		ret = -1;
+		goto out;
+	}
 
 	while ((i = read_in_full(cmd.out, namebuf, hexsz + 1)) == hexsz + 1) {
 		struct object_id oid;
@@ -736,10 +739,16 @@ static int get_reachable_list(struct upload_pack_data *data,
 	}
 	close(cmd.out);
 
-	if (finish_command(&cmd))
-		return -1;
+	if (finish_command(&cmd)) {
+		ret = -1;
+		goto out;
+	}
 
-	return 0;
+	ret = 0;
+
+out:
+	child_process_clear(&cmd);
+	return ret;
 }
 
 static int has_unreachable(struct object_array *src, enum allow_uor allow_uor)
@@ -749,7 +758,7 @@ static int has_unreachable(struct object_array *src, enum allow_uor allow_uor)
 	int i;
 
 	if (do_reachable_revlist(&cmd, src, NULL, allow_uor) < 0)
-		return 1;
+		goto error;
 
 	/*
 	 * The commits out of the rev-list are not ancestors of
@@ -775,6 +784,7 @@ static int has_unreachable(struct object_array *src, enum allow_uor allow_uor)
 error:
 	if (cmd.out >= 0)
 		close(cmd.out);
+	child_process_clear(&cmd);
 	return 1;
 }