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([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7703ffae973sm117987b3a.12.2025.08.22.07.28.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Aug 2025 07:28:16 -0700 (PDT) From: Jeongjun Park To: mchehab@kernel.org Cc: hverkuil@kernel.org, laurent.pinchart+renesas@ideasonboard.com, crope@iki.fi, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+6ffd76b5405c006a46b7@syzkaller.appspotmail.com, syzbot+f1b20958f93d2d250727@syzkaller.appspotmail.com, Jeongjun Park Subject: [PATCH] media: hackrf: fix to not free memory after the device is registered in hackrf_probe() Date: Fri, 22 Aug 2025 23:27:29 +0900 Message-Id: <20250822142729.1156816-1-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=y Content-Transfer-Encoding: 8bit In hackrf driver, the following race condition occurs: --- CPU0 CPU1 hackrf_probe() kzalloc(); // alloc hackrf_dev .... v4l2_device_register(); .... open("/path/to/dev"); // open hackrf dev .... v4l2_device_unregister(); .... kfree(); // free hackrf_dev .... ioctl(fd, ...); v4l2_ioctl(); video_is_registered() // UAF!! .... close(fd); v4l2_release() // UAF!! hackrf_video_release() kfree(); // DFB!! --- When a V4L2 or video device is unregistered, the device node is removed so new open() calls are blocked. However, file descriptors that are already open—and any in-flight I/O—do not terminate immediately; they remain valid until the last reference is dropped and the driver’s release() is invoked. Therefore, freeing device memory on the error path after hackrf_probe() has registered dev it will lead to a race to use-after-free vuln, since those already-open handles haven’t been released yet. And since release() free memory too, race to use-after-free and double-free vuln occur. To prevent this, if device is registered from probe(), it should be modified to free memory only through release() rather than calling kfree() directly. Reported-by: syzbot+6ffd76b5405c006a46b7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=6ffd76b5405c006a46b7 Reported-by: syzbot+f1b20958f93d2d250727@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f1b20958f93d2d250727 Fixes: 8bc4a9ed8504 ("[media] hackrf: add support for transmitter") Signed-off-by: Jeongjun Park --- drivers/media/usb/hackrf/hackrf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/media/usb/hackrf/hackrf.c b/drivers/media/usb/hackrf/hackrf.c index 0b50de8775a3..d7a84422193d 100644 --- a/drivers/media/usb/hackrf/hackrf.c +++ b/drivers/media/usb/hackrf/hackrf.c @@ -1515,6 +1515,8 @@ static int hackrf_probe(struct usb_interface *intf, video_unregister_device(&dev->rx_vdev); err_v4l2_device_unregister: v4l2_device_unregister(&dev->v4l2_dev); + dev_dbg(&intf->dev, "failed=%d\n", ret); + return ret; err_v4l2_ctrl_handler_free_tx: v4l2_ctrl_handler_free(&dev->tx_ctrl_handler); err_v4l2_ctrl_handler_free_rx: --