Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
From:   SeongJae Park <sj@kernel.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     SeongJae Park <sj@kernel.org>, damon@lists.linux.dev,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: [PATCH 3/3] mm/damon/sysfs-schemes: handle tried region directory allocation failure
Date:   Mon,  6 Nov 2023 23:34:08 +0000
Message-Id: <20231106233408.51159-4-sj@kernel.org>
In-Reply-To: <20231106233408.51159-1-sj@kernel.org>
References: <20231106233408.51159-1-sj@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

DAMON sysfs interface's before_damos_apply callback
(damon_sysfs_before_damos_apply()), which creates the DAMOS tried
regions for each DAMOS action applied region, is not handling the
allocation failure for the sysfs directory data.  As a result, NULL
pointer derefeence is possible.  Fix it by handling the case.

Fixes: f1d13cacabe1 ("mm/damon/sysfs: implement DAMOS tried regions update command")
Cc: <stable@vger.kernel.org> # 6.2.x
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 7413cb35c5a9..be667236b8e6 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1826,6 +1826,8 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
 		return 0;
 
 	region = damon_sysfs_scheme_region_alloc(r);
+	if (!region)
+		return 0;
 	list_add_tail(&region->list, &sysfs_regions->regions_list);
 	sysfs_regions->nr_regions++;
 	if (kobject_init_and_add(&region->kobj,
-- 
2.34.1