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([2405:4802:1d4a:e90:2022:c2a9:de8:d005]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39e6c6dd585sm8490548a91.0.2026.09.20.04.39.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Sep 2026 04:40:01 -0700 (PDT) From: Nguyen Ngoc Thang To: dmitry.torokhov@gmail.com Cc: floe@butterbrot.org, linux-input@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Nguyen Ngoc Thang , syzbot+eb4706daf505f9c4b547@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH v1 2/2] Input: sur40 - keep device state alive until the video node is released Date: Sun, 20 Sep 2026 18:39:49 +0700 Message-ID: <20260920113949.12726-3-ngocthang2710.1999@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260920113949.12726-1-ngocthang2710.1999@gmail.com> References: <20260920113949.12726-1-ngocthang2710.1999@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit sur40_disconnect() frees the sur40_state, which embeds the video_device, the v4l2_device and the vb2_queue, while a video node may still be open. Closing that file afterwards touches freed memory: BUG: KASAN: slab-use-after-free in vb2_core_queue_release+0x12d/0x150 Read of size 4 at addr ffff888066fa8aa8 by task v4l_id/28733 vb2_core_queue_release+0x12d/0x150 vb2_fop_release+0x16e/0x200 v4l2_release+0x22c/0x350 __fput+0x418/0xa50 Freed by task 16811: kfree+0x1c5/0x650 sur40_disconnect+0xaf/0x140 Give the v4l2_device a release callback that frees the bulk buffer and the state, and drop the disconnect path's own reference with v4l2_device_put(). The last closer of the node then does the freeing. The probe error paths never open the node and keep freeing directly. Reported-by: syzbot+eb4706daf505f9c4b547@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=eb4706daf505f9c4b547 Fixes: e831cd251fb9 ("[media] add raw video stream support for Samsung SUR40") Cc: stable@vger.kernel.org Signed-off-by: Nguyen Ngoc Thang --- drivers/input/touchscreen/sur40.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/input/touchscreen/sur40.c b/drivers/input/touchscreen/sur40.c index 7020bcf9b81a..efd4fe557cef 100644 --- a/drivers/input/touchscreen/sur40.c +++ b/drivers/input/touchscreen/sur40.c @@ -648,6 +648,15 @@ static int sur40_input_setup_events(struct input_dev *input_dev) } /* Check candidate USB interface. */ +/* Runs once the last video node reference is gone. */ +static void sur40_release(struct v4l2_device *v4l2) +{ + struct sur40_state *sur40 = container_of(v4l2, struct sur40_state, v4l2); + + kfree(sur40->bulk_in_buffer); + kfree(sur40); +} + static int sur40_probe(struct usb_interface *interface, const struct usb_device_id *id) { @@ -733,6 +742,7 @@ static int sur40_probe(struct usb_interface *interface, "Unable to register video master device."); goto err_free_buffer; } + sur40->v4l2.release = sur40_release; /* initialize the lock and subdevice */ sur40->queue = sur40_queue; @@ -831,11 +841,10 @@ static void sur40_disconnect(struct usb_interface *interface) video_unregister_device(&sur40->vdev); v4l2_device_unregister(&sur40->v4l2); - kfree(sur40->bulk_in_buffer); - kfree(sur40); - usb_set_intfdata(interface, NULL); dev_dbg(&interface->dev, "%s is now disconnected\n", DRIVER_DESC); + + v4l2_device_put(&sur40->v4l2); } /* -- 2.43.0