Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.3 72/95] media: usbvision: Fix invalid accesses after device disconnect | Date | Wed, 27 Nov 2019 21:32:29 +0100 |
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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> CC: <stable@vger.kernel.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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 @@ -453,6 +453,9 @@ static int vidioc_querycap(struct file * { 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, @@ -1111,8 +1114,9 @@ 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, - usbvision->iface_alt); + if (usbvision->dev) + usb_set_interface(usbvision->dev, usbvision->iface, + usbvision->iface_alt); usbvision_audio_off(usbvision); usbvision->radio = 0;
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