[PATCH] selftests/cgroup: free the paths returned by cg_control()

[Sasha Levin <sashal@kernel.org>]

cg_control() returns a path allocated with malloc(). The two callers
that pass it straight to inotify_add_watch() never free it, and pass
NULL to it if the allocation fails.

Keep the path in a local variable, check it, and free it when done.

Fixes: 5313bfe425c8a ("kselftests: cgroup: add freezer controller self-tests")
Fixes: 2de27980e1d46 ("selftests: memcg: Add tests for IN_DELETE_SELF and IN_IGNORED")
Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/testing/selftests/cgroup/lib/cgroup_util.c | 13 ++++++++++---
 tools/testing/selftests/cgroup/test_memcontrol.c |  9 +++++++--
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/cgroup/lib/cgroup_util.c b/tools/testing/selftests/cgroup/lib/cgroup_util.c
index 2596c12cd8645..ed99a235e76e1 100644
--- a/tools/testing/selftests/cgroup/lib/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c
@@ -626,18 +626,25 @@ int clone_into_cgroup_run_wait(const char *cgroup)
 
 static int __prepare_for_wait(const char *cgroup, const char *filename)
 {
-	int fd, ret = -1;
+	char *path;
+	int fd, ret;
+
+	path = cg_control(cgroup, filename);
+	if (!path)
+		return -1;
 
 	fd = inotify_init1(0);
 	if (fd == -1)
-		return fd;
+		goto out;
 
-	ret = inotify_add_watch(fd, cg_control(cgroup, filename), IN_MODIFY);
+	ret = inotify_add_watch(fd, path, IN_MODIFY);
 	if (ret == -1) {
 		close(fd);
 		fd = -1;
 	}
 
+out:
+	free(path);
 	return fd;
 }
 
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 047d487f6dd57..7bcf772bcea2d 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -1677,7 +1677,7 @@ static int read_event(int inotify_fd, int expected_event, int expected_wd)
 static int test_memcg_inotify_delete_file(const char *root)
 {
 	int ret = KSFT_FAIL;
-	char *memcg = NULL;
+	char *memcg = NULL, *events = NULL;
 	int fd = -1, wd;
 
 	memcg = cg_name(root, "memcg_test_0");
@@ -1692,7 +1692,11 @@ static int test_memcg_inotify_delete_file(const char *root)
 	if (fd == -1)
 		goto cleanup;
 
-	wd = inotify_add_watch(fd, cg_control(memcg, "memory.events"), IN_DELETE_SELF);
+	events = cg_control(memcg, "memory.events");
+	if (!events)
+		goto cleanup;
+
+	wd = inotify_add_watch(fd, events, IN_DELETE_SELF);
 	if (wd == -1)
 		goto cleanup;
 
@@ -1714,6 +1718,7 @@ static int test_memcg_inotify_delete_file(const char *root)
 		close(fd);
 	if (memcg)
 		cg_destroy(memcg);
+	free(events);
 	free(memcg);
 
 	return ret;
-- 
2.53.0