From: Alan Stern <stern@rowland.harvard.edu>
To: Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil@xs4all.nl>
Cc: linux-media@vger.kernel.org, USB list <linux-usb@vger.kernel.org>,
<syzkaller-bugs@googlegroups.com>
Subject: [PATCH 1/2 RESEND] media: usbvision: Fix invalid accesses after device disconnect
Date: Mon, 7 Oct 2019 11:09:04 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1910071100170.1513-100000@iolanthe.rowland.org> (raw)
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>
---
[as1919]
drivers/media/usb/usbvision/usbvision-video.c | 6 +++++-
1 file changed, 5 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 +453,9 @@ 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,
@@ -1111,7 +1114,8 @@ 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);
reply other threads:[~2019-10-07 15:09 UTC|newest]
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