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

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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@vger.kernel.org>     # 2.6.21
Cc: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Johan Hovold <johan@kernel.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

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[PATCH 0/6] [media] fix missing endpoint sanity checks Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 3/6] [media] cx231xx-cards: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 4/6] [media] cx231xx-audio: fix init error path Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 5/6] [media] cx231xx-audio: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 2/6] [media] usbvision: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 1/6] [media] dib0700: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  [PATCH 6/6] [media] gspca: konica: add missing endpoint sanity check Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100

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