[PATCH v5] damon/sysfs: fix possible memleak on damon_sysfs_add_target

[PATCH v5] damon/sysfs: fix possible memleak on damon_sysfs_add_target

[SeongJae Park]

From: Levi Yun <ppbuk5246@gmail.com>

When damon_sysfs_add_target couldn't find proper task, newly allocated
damon_target structure isn't registered yet.  So, it's impossible to
free the newly allocated one by damon_sysfs_destroy_targets.

By calling damon_add_target as soon as allocating new target, fix this
possible memory leak.

Fixes: a61ea561c871 ("mm/damon/sysfs: link DAMON for virtual address spaces monitoring")
Cc: <stable@vger.kernel.org> # 5.17.x
Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
---

Changes from v4
(https://lore.kernel.org/damon/20220926160611.48536-1-sj@kernel.org/_
- Fix some typos

Changes from v3
(https://lore.kernel.org/damon/20220925234327.26345-1-ppbuk5246@gmail.com/)
- Fix Fixes: tag
- Add patch changelog

Changes from v2
(https://lore.kernel.org/damon/20220925234053.26090-1-ppbuk5246@gmail.com/)
- Add Fixes: and Cc: stable

Changes from v1
(https://lore.kernel.org/damon/20220925140257.23431-1-ppbuk5246@gmail.com/)
- Do damon_add_target() earlier instead of explicitly freeing the object

 mm/damon/sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 455215a5c059..9f1219a67e3f 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -2172,12 +2172,12 @@ static int damon_sysfs_add_target(struct damon_sysfs_target *sys_target,
 
 	if (!t)
 		return -ENOMEM;
+	damon_add_target(ctx, t);
 	if (damon_target_has_pid(ctx)) {
 		t->pid = find_get_pid(sys_target->pid);
 		if (!t->pid)
 			goto destroy_targets_out;
 	}
-	damon_add_target(ctx, t);
 	err = damon_sysfs_set_regions(t, sys_target->regions);
 	if (err)
 		goto destroy_targets_out;
-- 
2.25.1