[PATCH] media: uvcvideo: Fix bounds for descriptor parsing

[Ricardo Ribalda <ribalda@chromium.org>]

uvc_parse_control() passes descriptor by descriptor to
uvc_parse_standard_control() with the number of bytes remaining in the
buffer, not the number of bytes of that descriptor.

Because of this, malformed descriptors could leak over the next
descriptor, leaving malformed data in our structures.

Change the code so we pass the actual length of the descriptor to the
parser.

Note that this makes the existing check more strict and some devices
that are wrongly parsed today will not be probed now.

Cc: stable@vger.kernel.org
Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index e289cc71ba98..429f1ab19a2a 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1248,11 +1248,14 @@ static int uvc_parse_control(struct uvc_device *dev)
 	 */
 
 	while (buflen > 2) {
-		if (uvc_parse_vendor_control(dev, buffer, buflen) ||
+		if (buflen < buffer[0] || buffer[0] < 3)
+			return -EINVAL;
+
+		if (uvc_parse_vendor_control(dev, buffer, buffer[0]) ||
 		    buffer[1] != USB_DT_CS_INTERFACE)
 			goto next_descriptor;
 
-		ret = uvc_parse_standard_control(dev, buffer, buflen);
+		ret = uvc_parse_standard_control(dev, buffer, buffer[0]);
 		if (ret < 0)
 			return ret;
 

---
base-commit: 27953c044974baf7e24dee3e9342fe0103dea80c
change-id: 20260911-uvc-ctrl-bound-9c1940f06fc7

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>