[PATCH 3.16 034/134] [media] usbvision: fix NULL-deref at probe

Ben Hutchings
2017-08-18T13:13:20Z

From: Johan Hovold <johan@kernel.org>

commit eacb975b48272f54532b62f515a3cf7eefa35123 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer or accessing memory beyond the endpoint array should a
malicious device lack the expected endpoints.

Fixes: 2a9f8b5d25be ("V4L/DVB (5206): Usbvision: set alternate interface
modification")

Cc: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/media/usb/usbvision/usbvision-video.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1599,7 +1599,14 @@ static int usbvision_probe(struct usb_in
}

for (i = 0; i < usbvision->num_alt; i++) {
- u16 tmp = le16_to_cpu(uif->altsetting[i].endpoint[1].desc.
+ u16 tmp;
+
+ if (uif->altsetting[i].desc.bNumEndpoints < 2) {
+ ret = -ENODEV;
+ goto err_pkt;
+ }
+
+ tmp = le16_to_cpu(uif->altsetting[i].endpoint[1].desc.
wMaxPacketSize);
usbvision->alt_max_pkt_size[i] =
(tmp & 0x07ff) * (((tmp & 0x1800) >> 11) + 1);