1 files changed, 63 insertions, 12 deletions

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index aa6ab666741a..73dc7e42875f 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -362,6 +362,10 @@ uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
 			return ret;
 		usb_ep_enable(uvc->video.ep);
 
+		uvc->video.max_req_size = uvc->video.ep->maxpacket
+			* max_t(unsigned int, uvc->video.ep->maxburst, 1)
+			* (uvc->video.ep->mult);
+
 		memset(&v4l2_event, 0, sizeof(v4l2_event));
 		v4l2_event.type = UVC_EVENT_STREAMON;
 		v4l2_event_queue(&uvc->vdev, &v4l2_event);
@@ -409,6 +413,12 @@ uvc_function_disconnect(struct uvc_device *uvc)
 {
 	int ret;
 
+	guard(mutex)(&uvc->lock);
+	if (uvc->func_unbound) {
+		dev_dbg(&uvc->vdev.dev, "skipping function deactivate (unbound)\n");
+		return;
+	}
+
 	if ((ret = usb_function_deactivate(&uvc->func)) < 0)
 		uvcg_info(&uvc->func, "UVC disconnect failed with %d\n", ret);
 }
@@ -427,6 +437,15 @@ static ssize_t function_name_show(struct device *dev,
 
 static DEVICE_ATTR_RO(function_name);
 
+static void uvc_vdev_release(struct video_device *vdev)
+{
+	struct uvc_device *uvc = video_get_drvdata(vdev);
+
+	/* Signal uvc_function_unbind() that the video device has been released */
+	if (uvc->vdev_release_done)
+		complete(uvc->vdev_release_done);
+}
+
 static int
 uvc_register_video(struct uvc_device *uvc)
 {
@@ -439,7 +458,7 @@ uvc_register_video(struct uvc_device *uvc)
 	uvc->vdev.v4l2_dev->dev = &cdev->gadget->dev;
 	uvc->vdev.fops = &uvc_v4l2_fops;
 	uvc->vdev.ioctl_ops = &uvc_v4l2_ioctl_ops;
-	uvc->vdev.release = video_device_release_empty;
+	uvc->vdev.release = uvc_vdev_release;
 	uvc->vdev.vfl_dir = VFL_DIR_TX;
 	uvc->vdev.lock = &uvc->video.mutex;
 	uvc->vdev.device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
@@ -655,6 +674,8 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 	int ret = -EINVAL;
 
 	uvcg_info(f, "%s()\n", __func__);
+	scoped_guard(mutex, &uvc->lock)
+		uvc->func_unbound = false;
 
 	opts = fi_to_f_uvc_opts(f->fi);
 	/* Sanity check the streaming endpoint module parameters. */
@@ -748,6 +769,16 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 	uvc_ss_streaming_ep.bEndpointAddress = uvc->video.ep->address;
 
 	/*
+	 * Hold opts->lock across both the XU string-descriptor fixup below and
+	 * the descriptor-copy block further down.  Without this, configfs
+	 * uvcg_extension_drop() (which takes opts->lock) can race with the
+	 * list_for_each_entry() walks here and inside uvc_copy_descriptors(),
+	 * leading to a UAF on a freed struct uvcg_extension.  See
+	 * drivers/usb/gadget/function/uvc_configfs.c::uvcg_extension_drop().
+	 */
+	mutex_lock(&opts->lock);
+
+	/*
 	 * XUs can have an arbitrary string descriptor describing them. If they
 	 * have one pick up the ID.
 	 */
@@ -764,7 +795,7 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 				 ARRAY_SIZE(uvc_en_us_strings));
 	if (IS_ERR(us)) {
 		ret = PTR_ERR(us);
-		goto error;
+		goto error_unlock;
 	}
 
 	uvc_iad.iFunction = opts->iad_index ? cdev->usb_strings[opts->iad_index].id :
@@ -778,14 +809,14 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 
 	/* Allocate interface IDs. */
 	if ((ret = usb_interface_id(c, f)) < 0)
-		goto error;
+		goto error_unlock;
 	uvc_iad.bFirstInterface = ret;
 	uvc_control_intf.bInterfaceNumber = ret;
 	uvc->control_intf = ret;
 	opts->control_interface = ret;
 
 	if ((ret = usb_interface_id(c, f)) < 0)
-		goto error;
+		goto error_unlock;
 	uvc_streaming_intf_alt0.bInterfaceNumber = ret;
 	uvc_streaming_intf_alt1.bInterfaceNumber = ret;
 	uvc->streaming_intf = ret;
@@ -796,30 +827,32 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 	if (IS_ERR(f->fs_descriptors)) {
 		ret = PTR_ERR(f->fs_descriptors);
 		f->fs_descriptors = NULL;
-		goto error;
+		goto error_unlock;
 	}
 
 	f->hs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_HIGH);
 	if (IS_ERR(f->hs_descriptors)) {
 		ret = PTR_ERR(f->hs_descriptors);
 		f->hs_descriptors = NULL;
-		goto error;
+		goto error_unlock;
 	}
 
 	f->ss_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_SUPER);
 	if (IS_ERR(f->ss_descriptors)) {
 		ret = PTR_ERR(f->ss_descriptors);
 		f->ss_descriptors = NULL;
-		goto error;
+		goto error_unlock;
 	}
 
 	f->ssp_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_SUPER_PLUS);
 	if (IS_ERR(f->ssp_descriptors)) {
 		ret = PTR_ERR(f->ssp_descriptors);
 		f->ssp_descriptors = NULL;
-		goto error;
+		goto error_unlock;
 	}
 
+	mutex_unlock(&opts->lock);
+
 	/* Preallocate control endpoint request. */
 	uvc->control_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
 	uvc->control_buf = kmalloc(UVC_MAX_REQUEST_SIZE, GFP_KERNEL);
@@ -851,6 +884,8 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 
 	return 0;
 
+error_unlock:
+	mutex_unlock(&opts->lock);
 v4l2_error:
 	v4l2_device_unregister(&uvc->v4l2_dev);
 error:
@@ -883,7 +918,7 @@ static struct usb_function_instance *uvc_alloc_inst(void)
 	struct uvc_descriptor_header **ctl_cls;
 	int ret;
 
-	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	opts = kzalloc_obj(*opts);
 	if (!opts)
 		return ERR_PTR(-ENOMEM);
 	opts->func_inst.free_func_inst = uvc_free_inst;
@@ -984,12 +1019,19 @@ static void uvc_free(struct usb_function *f)
 static void uvc_function_unbind(struct usb_configuration *c,
 				struct usb_function *f)
 {
+	DECLARE_COMPLETION_ONSTACK(vdev_release_done);
 	struct usb_composite_dev *cdev = c->cdev;
 	struct uvc_device *uvc = to_uvc(f);
 	struct uvc_video *video = &uvc->video;
 	long wait_ret = 1;
+	bool connected;
 
 	uvcg_info(f, "%s()\n", __func__);
+	scoped_guard(mutex, &uvc->lock) {
+		uvc->func_unbound = true;
+		uvc->vdev_release_done = &vdev_release_done;
+		connected = uvc->func_connected;
+	}
 
 	kthread_cancel_work_sync(&video->hw_submit);
 
@@ -1002,7 +1044,7 @@ static void uvc_function_unbind(struct usb_configuration *c,
 	 * though the video device removal uevent. Allow some time for the
 	 * application to close out before things get deleted.
 	 */
-	if (uvc->func_connected) {
+	if (connected) {
 		uvcg_dbg(f, "waiting for clean disconnect\n");
 		wait_ret = wait_event_interruptible_timeout(uvc->func_connected_queue,
 				uvc->func_connected == false, msecs_to_jiffies(500));
@@ -1013,7 +1055,10 @@ static void uvc_function_unbind(struct usb_configuration *c,
 	video_unregister_device(&uvc->vdev);
 	v4l2_device_unregister(&uvc->v4l2_dev);
 
-	if (uvc->func_connected) {
+	scoped_guard(mutex, &uvc->lock)
+		connected = uvc->func_connected;
+
+	if (connected) {
 		/*
 		 * Wait for the release to occur to ensure there are no longer any
 		 * pending operations that may cause panics when resources are cleaned
@@ -1025,6 +1070,10 @@ static void uvc_function_unbind(struct usb_configuration *c,
 		uvcg_dbg(f, "done waiting for release with ret: %ld\n", wait_ret);
 	}
 
+	/* Wait for the video device to be released */
+	wait_for_completion(&vdev_release_done);
+	uvc->vdev_release_done = NULL;
+
 	usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
 	kfree(uvc->control_buf);
 
@@ -1038,11 +1087,13 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 	struct uvc_descriptor_header **strm_cls;
 	struct config_item *streaming, *header, *h;
 
-	uvc = kzalloc(sizeof(*uvc), GFP_KERNEL);
+	uvc = kzalloc_obj(*uvc);
 	if (uvc == NULL)
 		return ERR_PTR(-ENOMEM);
 
 	mutex_init(&uvc->video.mutex);
+	mutex_init(&uvc->lock);
+	uvc->func_unbound = true;
 	uvc->state = UVC_STATE_DISCONNECTED;
 	init_waitqueue_head(&uvc->func_connected_queue);
 	opts = fi_to_f_uvc_opts(fi);