linux-kernel - [PATCH 2/6] [media] usbvision: fix NULL-deref at probe

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Message-Id: <20170313125359.29394-3-johan@kernel.org>
Date:   Mon, 13 Mar 2017 13:53:55 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        stable <stable@...r.kernel.org>,
        Thierry MERLE <thierry.merle@...e.fr>
Subject: [PATCH 2/6] [media] usbvision: fix NULL-deref at probe

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: stable <stable@...r.kernel.org>     # 2.6.21
Cc: Thierry MERLE <thierry.merle@...e.fr>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/media/usb/usbvision/usbvision-video.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/usbvision/usbvision-video.c b/drivers/media/usb/usbvision/usbvision-video.c
index f5c635a67d74..f9c3325aa4d4 100644
--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1501,7 +1501,14 @@ static int usbvision_probe(struct usb_interface *intf,
 	}
 
 	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);
-- 
2.12.0