net: usb: smsc95xx: Limit packet length to skb->len

[ Upstream commit ff821092cf02a70c2bccd2d19269f01e29aa52cf ]

Packet length retrieved from descriptor may be larger than
the actual socket buffer length. In such case the cloned
skb passed up the network stack will leak kernel memory contents.

Fixes: 2f7ca802bdae ("net: Add SMSC LAN9500 USB2.0 10/100 ethernet adapter driver")
Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230316101954.75836-1-szymon.heidrich@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index 7cf9206638c37ed395151bf85c5b707981ed839f..649d9f9af6e678a06eef48d23355cc82d47200e8 100644 (file)
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -1808,6 +1808,12 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                size = (u16)((header & RX_STS_FL_) >> 16);
                align_count = (4 - ((size + NET_IP_ALIGN) % 4)) % 4;
 
+               if (unlikely(size > skb->len)) {
+                       netif_dbg(dev, rx_err, dev->net,
+                                 "size err header=0x%08x\n", header);
+                       return 0;
+               }
+
                if (unlikely(header & RX_STS_ES_)) {
                        netif_dbg(dev, rx_err, dev->net,
                                  "Error header=0x%08x\n", header);