UPSTREAM: sr9700: sanity check for packet length

[ Upstream commit e9da0b56fe27206b49f39805f7dcda8a89379062 ]

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

Bug: 225469258
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I2f17bd57b5c4228d0420f716527316a878a34efd

drivers/net/usb/sr9700.c

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index e04c8054..fce6713 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -410,7 +410,7 @@ 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 */