3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit c7a191464078262bf799136317c95824e26a222b upstream.
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: syzbot+7fa38a608b1075dfd634@syzkaller.appspotmail.com
Signed-off-by: Alan Stern stern@rowland.harvard.edu Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab+samsung@kernel.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/media/usb/usbvision/usbvision-video.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/media/usb/usbvision/usbvision-video.c +++ b/drivers/media/usb/usbvision/usbvision-video.c @@ -482,6 +482,9 @@ static int vidioc_querycap(struct file * { struct usb_usbvision *usbvision = video_drvdata(file);
+ if (!usbvision->dev) + return -ENODEV; + strlcpy(vc->driver, "USBVision", sizeof(vc->driver)); strlcpy(vc->card, usbvision_device_data[usbvision->dev_model].model_string, @@ -1169,8 +1172,9 @@ static int usbvision_radio_close(struct mutex_lock(&usbvision->v4l2_lock); /* Set packet size to 0 */ usbvision->iface_alt = 0; - err_code = usb_set_interface(usbvision->dev, usbvision->iface, - usbvision->iface_alt); + if (usbvision->dev) + err_code = usb_set_interface(usbvision->dev, usbvision->iface, + usbvision->iface_alt);
usbvision_audio_off(usbvision); usbvision->radio = 0;