On Mon, 16 Sep 2019, syzbot wrote: > Hello, > > syzbot has tested the proposed patch but the reproducer still triggered > crash: > general protection fault in vidioc_querycap Same problem in a different part of the code. Alan Stern #syz test: https://github.com/google/kasan.git f0df5c1b drivers/media/usb/usbvision/usbvision-video.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) Index: usb-devel/drivers/media/usb/usbvision/usbvision-video.c =================================================================== --- usb-devel.orig/drivers/media/usb/usbvision/usbvision-video.c +++ usb-devel/drivers/media/usb/usbvision/usbvision-video.c @@ -453,6 +453,12 @@ static int vidioc_querycap(struct file * { struct usb_usbvision *usbvision = video_drvdata(file); + mutex_lock(&usbvision->v4l2_lock); + if (!usbvision->dev) { + mutex_unlock(&usbvision->v4l2_lock); + return -ENODEV; + } + strscpy(vc->driver, "USBVision", sizeof(vc->driver)); strscpy(vc->card, usbvision_device_data[usbvision->dev_model].model_string, @@ -464,6 +470,7 @@ static int vidioc_querycap(struct file * vc->capabilities |= V4L2_CAP_RADIO; if (usbvision->have_tuner) vc->capabilities |= V4L2_CAP_TUNER; + mutex_unlock(&usbvision->v4l2_lock); return 0; } @@ -1111,7 +1118,8 @@ static int usbvision_radio_close(struct mutex_lock(&usbvision->v4l2_lock); /* Set packet size to 0 */ usbvision->iface_alt = 0; - usb_set_interface(usbvision->dev, usbvision->iface, + if (usbvision->dev) + usb_set_interface(usbvision->dev, usbvision->iface, usbvision->iface_alt); usbvision_audio_off(usbvision);
