object-name: fix leaking commit list items

When calling `get_oid_oneline()`, we pass in a `struct commit_list` that
gets modified by the function. This creates a weird situation where the
commit list may sometimes be empty after returning, but sometimes it
will continue to carry additional commits. In those cases the remainder
of the list leaks.

Ultimately, the design where we only pass partial ownership to
`get_oid_oneline()` feels shoddy. Refactor the code such that we only
pass a constant pointer to the list, creating a local copy as needed.
Callers are thus always responsible for freeing the commit list, which
then allows us to plug a bunch of memory leaks.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object-name.c

@@ -27,7 +27,8 @@
 #include "date.h"
 #include "object-file-convert.h"
 
-static int get_oid_oneline(struct repository *r, const char *, struct object_id *, struct commit_list *);
+static int get_oid_oneline(struct repository *r, const char *, struct object_id *,
+			   const struct commit_list *);
 
 typedef int (*disambiguate_hint_fn)(struct repository *, const struct object_id *, void *);
 
@@ -1254,6 +1255,8 @@ static int peel_onion(struct repository *r, const char *name, int len,
 		prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 		commit_list_insert((struct commit *)o, &list);
 		ret = get_oid_oneline(r, prefix, oid, list);
+
+		free_commit_list(list);
 		free(prefix);
 		return ret;
 	}
@@ -1388,9 +1391,10 @@ static int handle_one_ref(const char *path, const struct object_id *oid,
 
 static int get_oid_oneline(struct repository *r,
 			   const char *prefix, struct object_id *oid,
-			   struct commit_list *list)
+			   const struct commit_list *list)
 {
-	struct commit_list *backup = NULL, *l;
+	struct commit_list *copy = NULL;
+	const struct commit_list *l;
 	int found = 0;
 	int negative = 0;
 	regex_t regex;
@@ -1411,14 +1415,14 @@ static int get_oid_oneline(struct repository *r,
 
 	for (l = list; l; l = l->next) {
 		l->item->object.flags |= ONELINE_SEEN;
-		commit_list_insert(l->item, &backup);
+		commit_list_insert(l->item, &copy);
 	}
-	while (list) {
+	while (copy) {
 		const char *p, *buf;
 		struct commit *commit;
 		int matches;
 
-		commit = pop_most_recent_commit(&list, ONELINE_SEEN);
+		commit = pop_most_recent_commit(&copy, ONELINE_SEEN);
 		if (!parse_object(r, &commit->object.oid))
 			continue;
 		buf = repo_get_commit_buffer(r, commit, NULL);
@@ -1433,10 +1437,9 @@ static int get_oid_oneline(struct repository *r,
 		}
 	}
 	regfree(&regex);
-	free_commit_list(list);
-	for (l = backup; l; l = l->next)
+	for (l = list; l; l = l->next)
 		clear_commit_marks(l->item, ONELINE_SEEN);
-	free_commit_list(backup);
+	free_commit_list(copy);
 	return found ? 0 : -1;
 }
 
@@ -2024,7 +2027,10 @@ static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 			refs_for_each_ref(get_main_ref_store(repo), handle_one_ref, &cb);
 			refs_head_ref(get_main_ref_store(repo), handle_one_ref, &cb);
 			commit_list_sort_by_date(&list);
-			return get_oid_oneline(repo, name + 2, oid, list);
+			ret = get_oid_oneline(repo, name + 2, oid, list);
+
+			free_commit_list(list);
+			return ret;
 		}
 		if (namelen < 3 ||
 		    name[2] != ':' ||

t/t1511-rev-parse-caret.sh

@@ -5,6 +5,7 @@ test_description='tests for ref^{stuff}'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '

t/t6133-pathspec-rev-dwim.sh

@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='test dwim of revs versus pathspecs in revision parser'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' '