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From:   SeongJae Park <sj@kernel.org>
To:     akpm@linux-foundation.org
Cc:     ppbuk5246@gmail.com, damon@lists.linux.dev, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        SeongJae Park <sj@kernel.org>
Subject: [PATCH v4] damon/sysfs: Fix possible memleak on damon_sysfs_add_target.
Date:   Mon, 26 Sep 2022 16:06:11 +0000
Message-Id: <20220926160611.48536-1-sj@kernel.org>
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From: Levi Yun <ppbuk5246@gmail.com>

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

By calling daemon_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 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