sr9700: sanity check for packet length

A malicious device can leak heap data to user space
providing bogus frame lengths. Introduce a sanity check.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index b658510..5a53e63 100644 (file)
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -413,7 +413,7 @@ static int sr9700_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                /* ignore the CRC length */
                len = (skb->data[1] | (skb->data[2] << 8)) - 4;
 
-               if (len > ETH_FRAME_LEN)
+               if (len > ETH_FRAME_LEN || len > skb->len)
                        return 0;
 
                /* the last packet of current skb */