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>

diff --git a/drivers/net/usb/smsc75xx.c b/drivers/net/usb/smsc75xx.c
index 95de452ff4dad58f05e571b1e569a4d46a9129e2..db34f8d1d6051f9427f06e4edb42bda323da94bc 100644 (file)
--- a/drivers/net/usb/smsc75xx.c
+++ b/drivers/net/usb/smsc75xx.c
@@ -2212,7 +2212,8 @@ static int smsc75xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                                dev->net->stats.rx_frame_errors++;
                } else {
                        /* MAX_SINGLE_PACKET_SIZE + 4(CRC) + 2(COE) + 4(Vlan) */
-                       if (unlikely(size > (MAX_SINGLE_PACKET_SIZE + ETH_HLEN + 12))) {
+                       if (unlikely(size > (MAX_SINGLE_PACKET_SIZE + ETH_HLEN + 12) ||
+                                    size > skb->len)) {
                                netif_dbg(dev, rx_err, dev->net,
                                          "size err rx_cmd_a=0x%08x\n",
                                          rx_cmd_a);