net: usb: smsc75xx: Limit packet length to skb->len

net: usb: smsc75xx: Limit packet length to skb->len

[ Upstream commit 3c2ba0569ebce00c92baf3ebcc035bf8b4c97acb ]

Packet length retrieved from skb data may be larger than
the actual socket buffer length (up to 9026 bytes). In such
case the cloned skb passed up the network stack will leak
kernel memory contents.

Fixes: 1f4fa502fc00 ("smsc75xx: SMSC LAN75xx USB gigabit ethernet adapter driver")
Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>