diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 0f52e25249..3f2bfce8fa 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -96,10 +96,11 @@ static int sparse_checkout_list(int argc, const char **argv, const char *prefix)
 			printf("\n");
 		}
 
-		return 0;
+		string_list_clear(&sl, 0);
+	} else {
+		write_patterns_to_file(stdout, &pl);
 	}
 
-	write_patterns_to_file(stdout, &pl);
 	clear_pattern_list(&pl);
 
 	return 0;
@@ -205,11 +206,13 @@ static int update_working_directory(struct pattern_list *pl)
 	struct unpack_trees_options o;
 	struct lock_file lock_file = LOCK_INIT;
 	struct repository *r = the_repository;
+	struct pattern_list *old_pl;
 
 	/* If no branch has been checked out, there are no updates to make. */
 	if (is_index_unborn(r->index))
 		return UPDATE_SPARSITY_SUCCESS;
 
+	old_pl = r->index->sparse_checkout_patterns;
 	r->index->sparse_checkout_patterns = pl;
 
 	memset(&o, 0, sizeof(o));
@@ -241,7 +244,12 @@ static int update_working_directory(struct pattern_list *pl)
 
 	clean_tracked_sparse_directories(r);
 
-	r->index->sparse_checkout_patterns = NULL;
+	if (r->index->sparse_checkout_patterns != pl) {
+		clear_pattern_list(r->index->sparse_checkout_patterns);
+		FREE_AND_NULL(r->index->sparse_checkout_patterns);
+	}
+	r->index->sparse_checkout_patterns = old_pl;
+
 	return result;
 }
 
@@ -311,6 +319,8 @@ static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
 		fprintf(fp, "%s/\n", pattern);
 		free(pattern);
 	}
+
+	string_list_clear(&sl, 0);
 }
 
 static int write_patterns_and_update(struct pattern_list *pl)
@@ -440,7 +450,6 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix)
 	char *sparse_filename;
 	int res;
 	struct object_id oid;
-	struct strbuf pattern = STRBUF_INIT;
 
 	static struct option builtin_sparse_checkout_init_options[] = {
 		OPT_BOOL(0, "cone", &init_opts.cone_mode,
@@ -471,6 +480,7 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix)
 	/* If we already have a sparse-checkout file, use it. */
 	if (res >= 0) {
 		free(sparse_filename);
+		clear_pattern_list(&pl);
 		return update_working_directory(NULL);
 	}
 
@@ -491,10 +501,10 @@ static int sparse_checkout_init(int argc, const char **argv, const char *prefix)
 		return 0;
 	}
 
-	strbuf_addstr(&pattern, "/*");
-	add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0);
-	strbuf_addstr(&pattern, "!/*/");
-	add_pattern(strbuf_detach(&pattern, NULL), empty_base, 0, &pl, 0);
+	free(sparse_filename);
+
+	add_pattern("/*", empty_base, 0, &pl, 0);
+	add_pattern("!/*/", empty_base, 0, &pl, 0);
 	pl.use_cone_patterns = init_opts.cone_mode;
 
 	return write_patterns_and_update(&pl);
@@ -513,6 +523,7 @@ static void insert_recursive_pattern(struct pattern_list *pl, struct strbuf *pat
 		char *slash = strrchr(e->pattern, '/');
 		char *oldpattern = e->pattern;
 		size_t newlen;
+		struct pattern_entry *dup;
 
 		if (!slash || slash == e->pattern)
 			break;
@@ -523,8 +534,14 @@ static void insert_recursive_pattern(struct pattern_list *pl, struct strbuf *pat
 		e->pattern = xstrndup(oldpattern, newlen);
 		hashmap_entry_init(&e->ent, fspathhash(e->pattern));
 
-		if (!hashmap_get_entry(&pl->parent_hashmap, e, ent, NULL))
+		dup = hashmap_get_entry(&pl->parent_hashmap, e, ent, NULL);
+		if (!dup) {
 			hashmap_add(&pl->parent_hashmap, &e->ent);
+		} else {
+			free(e->pattern);
+			free(e);
+			e = dup;
+		}
 	}
 }
 
@@ -581,15 +598,15 @@ static void add_patterns_from_input(struct pattern_list *pl,
 				strbuf_to_cone_pattern(&line, pl);
 			}
 		}
+		strbuf_release(&line);
 	} else {
 		if (file) {
 			struct strbuf line = STRBUF_INIT;
 
-			while (!strbuf_getline(&line, file)) {
-				size_t len;
-				char *buf = strbuf_detach(&line, &len);
-				add_pattern(buf, empty_base, 0, pl, 0);
-			}
+			while (!strbuf_getline(&line, file))
+				add_pattern(line.buf, empty_base, 0, pl, 0);
+
+			strbuf_release(&line);
 		} else {
 			for (i = 0; i < argc; i++)
 				add_pattern(argv[i], empty_base, 0, pl, 0);
@@ -891,7 +908,6 @@ static int sparse_checkout_disable(int argc, const char **argv,
 		OPT_END(),
 	};
 	struct pattern_list pl;
-	struct strbuf match_all = STRBUF_INIT;
 
 	/*
 	 * We do not exit early if !core_apply_sparse_checkout; due to the
@@ -917,8 +933,7 @@ static int sparse_checkout_disable(int argc, const char **argv,
 	pl.use_cone_patterns = 0;
 	core_apply_sparse_checkout = 1;
 
-	strbuf_addstr(&match_all, "/*");
-	add_pattern(strbuf_detach(&match_all, NULL), empty_base, 0, &pl, 0);
+	add_pattern("/*", empty_base, 0, &pl, 0);
 
 	prepare_repo_settings(the_repository);
 	the_repository->settings.sparse_index = 0;
diff --git a/dir.c b/dir.c
index ad2b7ebe2d..45be4ad261 100644
--- a/dir.c
+++ b/dir.c
@@ -733,6 +733,17 @@ static char *dup_and_filter_pattern(const char *pattern)
 	return result;
 }
 
+static void clear_pattern_entry_hashmap(struct hashmap *map)
+{
+	struct hashmap_iter iter;
+	struct pattern_entry *entry;
+
+	hashmap_for_each_entry(map, &iter, entry, ent) {
+		free(entry->pattern);
+	}
+	hashmap_clear_and_free(map, struct pattern_entry, ent);
+}
+
 static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern *given)
 {
 	struct pattern_entry *translated;
@@ -806,6 +817,8 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 
 	if (given->patternlen > 2 &&
 	    !strcmp(given->pattern + given->patternlen - 2, "/*")) {
+		struct pattern_entry *old;
+
 		if (!(given->flags & PATTERN_FLAG_NEGATIVE)) {
 			/* Not a cone pattern. */
 			warning(_("unrecognized pattern: '%s'"), given->pattern);
@@ -831,7 +844,11 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 		}
 
 		hashmap_add(&pl->parent_hashmap, &translated->ent);
-		hashmap_remove(&pl->recursive_hashmap, &translated->ent, &data);
+		old = hashmap_remove_entry(&pl->recursive_hashmap, translated, ent, &data);
+		if (old) {
+			free(old->pattern);
+			free(old);
+		}
 		free(data);
 		return;
 	}
@@ -862,8 +879,8 @@ static void add_pattern_to_hashsets(struct pattern_list *pl, struct path_pattern
 
 clear_hashmaps:
 	warning(_("disabling cone pattern matching"));
-	hashmap_clear_and_free(&pl->parent_hashmap, struct pattern_entry, ent);
-	hashmap_clear_and_free(&pl->recursive_hashmap, struct pattern_entry, ent);
+	clear_pattern_entry_hashmap(&pl->recursive_hashmap);
+	clear_pattern_entry_hashmap(&pl->parent_hashmap);
 	pl->use_cone_patterns = 0;
 }
 
@@ -915,12 +932,7 @@ void add_pattern(const char *string, const char *base,
 	int nowildcardlen;
 
 	parse_path_pattern(&string, &patternlen, &flags, &nowildcardlen);
-	if (flags & PATTERN_FLAG_MUSTBEDIR) {
-		FLEXPTR_ALLOC_MEM(pattern, pattern, string, patternlen);
-	} else {
-		pattern = xmalloc(sizeof(*pattern));
-		pattern->pattern = string;
-	}
+	FLEX_ALLOC_MEM(pattern, pattern, string, patternlen);
 	pattern->patternlen = patternlen;
 	pattern->nowildcardlen = nowildcardlen;
 	pattern->base = base;
@@ -962,9 +974,8 @@ void clear_pattern_list(struct pattern_list *pl)
 	for (i = 0; i < pl->nr; i++)
 		free(pl->patterns[i]);
 	free(pl->patterns);
-	free(pl->filebuf);
-	hashmap_clear_and_free(&pl->recursive_hashmap, struct pattern_entry, ent);
-	hashmap_clear_and_free(&pl->parent_hashmap, struct pattern_entry, ent);
+	clear_pattern_entry_hashmap(&pl->recursive_hashmap);
+	clear_pattern_entry_hashmap(&pl->parent_hashmap);
 
 	memset(pl, 0, sizeof(*pl));
 }
@@ -1162,6 +1173,7 @@ static int add_patterns(const char *fname, const char *base, int baselen,
 	}
 
 	add_patterns_from_buffer(buf, size, base, baselen, pl);
+	free(buf);
 	return 0;
 }
 
@@ -1169,16 +1181,15 @@ static int add_patterns_from_buffer(char *buf, size_t size,
 				    const char *base, int baselen,
 				    struct pattern_list *pl)
 {
+	char *orig = buf;
 	int i, lineno = 1;
 	char *entry;
 
 	hashmap_init(&pl->recursive_hashmap, pl_hashmap_cmp, NULL, 0);
 	hashmap_init(&pl->parent_hashmap, pl_hashmap_cmp, NULL, 0);
 
-	pl->filebuf = buf;
-
 	if (skip_utf8_bom(&buf, size))
-		size -= buf - pl->filebuf;
+		size -= buf - orig;
 
 	entry = buf;
 
@@ -1225,6 +1236,7 @@ int add_patterns_from_blob_to_list(
 	}
 
 	add_patterns_from_buffer(buf, size, base, baselen, pl);
+	free(buf);
 	return 0;
 }
 
diff --git a/dir.h b/dir.h
index b9e8e96128..1398a53fb4 100644
--- a/dir.h
+++ b/dir.h
@@ -62,7 +62,6 @@ struct path_pattern {
 	 */
 	struct pattern_list *pl;
 
-	const char *pattern;
 	int patternlen;
 	int nowildcardlen;
 	const char *base;
@@ -74,6 +73,8 @@ struct path_pattern {
 	 * and from -1 decrementing for patterns from CLI args.
 	 */
 	int srcpos;
+
+	char pattern[FLEX_ARRAY];
 };
 
 /* used for hashmaps for cone patterns */
@@ -94,9 +95,6 @@ struct pattern_list {
 	int nr;
 	int alloc;
 
-	/* remember pointer to exclude file contents so we can free() */
-	char *filebuf;
-
 	/* origin of list, e.g. path to filename, or descriptive string */
 	const char *src;
 
diff --git a/t/t1090-sparse-checkout-scope.sh b/t/t1090-sparse-checkout-scope.sh
index 3a14218b24..da0e7714d5 100755
--- a/t/t1090-sparse-checkout-scope.sh
+++ b/t/t1090-sparse-checkout-scope.sh
@@ -6,6 +6,7 @@ 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
 
 test_expect_success 'setup' '
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index ab3a105fff..8c5cd651b4 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -8,6 +8,7 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 GIT_TEST_SPLIT_INDEX=false
 export GIT_TEST_SPLIT_INDEX
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 list_files() {
diff --git a/t/t3602-rm-sparse-checkout.sh b/t/t3602-rm-sparse-checkout.sh
index 08580fd3dc..fcdefba48c 100755
--- a/t/t3602-rm-sparse-checkout.sh
+++ b/t/t3602-rm-sparse-checkout.sh
@@ -2,6 +2,7 @@
 
 test_description='git rm in sparse checked out working trees'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup' "
diff --git a/t/t7002-mv-sparse-checkout.sh b/t/t7002-mv-sparse-checkout.sh
index 26582ae4e5..57969ce805 100755
--- a/t/t7002-mv-sparse-checkout.sh
+++ b/t/t7002-mv-sparse-checkout.sh
@@ -2,6 +2,7 @@
 
 test_description='git mv in sparse working trees'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 setup_sparse_checkout () {