net: check for underlength tap writes
If the user gives a packet under 14 bytes, we'll end up reading off the end
of the skb (not oopsing, just reading off the end).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Max Krasnyanskiy <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 970ec47..5b5d875 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -286,8 +286,11 @@
return -EFAULT;
}
- if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
+ if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
align = NET_IP_ALIGN;
+ if (unlikely(len < ETH_HLEN))
+ return -EINVAL;
+ }
if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
tun->dev->stats.rx_dropped++;