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

[ Upstream commit d8b228318935044dafe3a5bc07ee71a1f1424b8d ]

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 aa848be459ec7b73193898f1ca7bc8d16ab03e67..229ff92e41cd97cc556774c244d6192be86ac6d1 100644 (file)
--- a/drivers/net/usb/smsc75xx.c
+++ b/drivers/net/usb/smsc75xx.c
@@ -2210,7 +2210,8 @@ 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);