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[24.150.189.55]) by smtp.googlemail.com with ESMTPSA id 6a1803df08f44-6d8dabfb438sm40539386d6.106.2024.12.08.09.53.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Dec 2024 09:53:28 -0800 (PST) From: Dennis Lam To: richard@nod.at, chengzhihao1@huawei.com, miquel.raynal@bootlin.com, vigneshr@ti.com Cc: linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, syzbot+0988a383ae7c57b99dd9@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, Dennis Lam Subject: [PATCH] MTD: fix slab-use-after-free due to dangling pointer in notifier chain Date: Sun, 8 Dec 2024 12:52:12 -0500 Message-ID: <20241208175211.9406-2-dennis.lamerice@gmail.com> X-Mailer: git-send-email 2.47.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When attaching MTDs, a reboot notifier is added to the blocking notification chain. However, when detaching a MTD and freeing its related objects, the notifier is never unregistered from the notification chain and is freed during the detaching process. This results in the slab-use-after-free. To fix this, I added an unregister notifier function in the ubi_wl_close function to ensure that the notifier is removed from the chain after the device has been detached. Signed-off-by: Dennis Lam Reported-by: syzbot+0988a383ae7c57b99dd9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67409091.050a0220.363a1b.013d.GAE@googl= e.com/T/ --- drivers/mtd/ubi/wl.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c index 4f6f339d8fb8..31a1e5515d98 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -1995,6 +1995,7 @@ static void protection_queue_destroy(struct ubi_devic= e *ubi) void ubi_wl_close(struct ubi_device *ubi) { dbg_wl("close the WL sub-system"); + unregister_reboot_notifier(&ubi->wl_reboot_notifier); ubi_fastmap_close(ubi); shutdown_work(ubi); protection_queue_destroy(ubi); --=20 2.47.0