linux-kernel - [PATCH 4.5 053/200] [media] usbvision: revert commit 588afcc1

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Message-Id: <20160503000556.341217086@linuxfoundation.org>
Date:	Mon,  2 May 2016 17:10:52 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Vladis Dronov <vdronov@...hat.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>
Subject: [PATCH 4.5 053/200] [media] usbvision: revert commit 588afcc1

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vladis Dronov <vdronov@...hat.com>

commit d5468d7afaa9c9e961e150f0455a14a9f4872a98 upstream.

Commit 588afcc1c0e4 ("[media] usbvision fix overflow of interfaces
array")' should be reverted, because:

* "!dev->actconfig->interface[ifnum]" won't catch a case where the value
is not NULL but some garbage. This way the system may crash later with
GPF.

* "(ifnum >= USB_MAXINTERFACES)" does not cover all the error
conditions. "ifnum" should be compared to "dev->actconfig->
desc.bNumInterfaces", i.e. compared to the number of "struct
usb_interface" kzalloc()-ed, not to USB_MAXINTERFACES.

* There is a "struct usb_device" leak in this error path, as there is
usb_get_dev(), but no usb_put_dev() on this path.

* There is a bug of the same type several lines below with number of
endpoints. The code is accessing hard-coded second endpoint
("interface->endpoint[1].desc") which may not exist. It would be great
to handle this in the same patch too.

* All the concerns above are resolved by already-accepted commit fa52bd50
("[media] usbvision: fix crash on detecting device with invalid
configuration")

* Mailing list message:
http://www.spinics.net/lists/linux-media/msg94832.html

Signed-off-by: Vladis Dronov <vdronov@...hat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@...co.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@....samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/usb/usbvision/usbvision-video.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1461,13 +1461,6 @@ static int usbvision_probe(struct usb_in
 	printk(KERN_INFO "%s: %s found\n", __func__,
 				usbvision_device_data[model].model_string);

-	/*
-	 * this is a security check.
-	 * an exploit using an incorrect bInterfaceNumber is known
-	 */
-	if (ifnum >= USB_MAXINTERFACES || !dev->actconfig->interface[ifnum])
-		return -ENODEV;
-
 	if (usbvision_device_data[model].interface >= 0)
 		interface = &dev->actconfig->interface[usbvision_device_data[model].interface]->altsetting[0];
 	else if (ifnum < dev->actconfig->desc.bNumInterfaces)