Commit c7a19146 authored by Alan Stern's avatar Alan Stern Committed by Mauro Carvalho Chehab
Browse files

media: usbvision: Fix invalid accesses after device disconnect 



The syzbot fuzzer found two invalid-access bugs in the usbvision
driver.  These bugs occur when userspace keeps the device file open
after the device has been disconnected and usbvision_disconnect() has
set usbvision->dev to NULL:

	When the device file is closed, usbvision_radio_close() tries
	to issue a usb_set_interface() call, passing the NULL pointer
	as its first argument.

	If userspace performs a querycap ioctl call, vidioc_querycap()
	calls usb_make_path() with the same NULL pointer.

This patch fixes the problems by making the appropriate tests
beforehand.  Note that vidioc_querycap() is protected by
usbvision->v4l2_lock, acquired in a higher layer of the V4L2
subsystem.

Reported-and-tested-by: default avatar <syzbot+7fa38a608b1075dfd634@syzkaller.appspotmail.com>

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent 59251a8b

drivers/media/usb/usbvision/usbvision-video.c

+6 −2
Original line number Diff line number Diff line
@@ -453,6 +453,9 @@ static int vidioc_querycap(struct file *file, void *priv, 
{

	struct usb_usbvision *usbvision = video_drvdata(file);



	if (!usbvision->dev)

		return -ENODEV;



	strscpy(vc->driver, "USBVision", sizeof(vc->driver));

	strscpy(vc->card,

		usbvision_device_data[usbvision->dev_model].model_string,
@@ -1099,6 +1102,7 @@ static int usbvision_radio_close(struct file *file) 
	mutex_lock(&usbvision->v4l2_lock);

	/* Set packet size to 0 */

	usbvision->iface_alt = 0;

	if (usbvision->dev)

		usb_set_interface(usbvision->dev, usbvision->iface,

				  usbvision->iface_alt);