Commit 113f99c3 authored May 17, 2018 by Willem de Bruijn Committed by David S. Miller May 17, 2018

net: test tailroom before appending to linear skb



Device features may change during transmission. In particular with
corking, a device may toggle scatter-gather in between allocating
and writing to an skb.

Do not unconditionally assume that !NETIF_F_SG at write time implies
that the same held at alloc time and thus the skb has sufficient
tailroom.

This issue predates git history.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 374edea4

net/ipv4/ip_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1045,7 +1045,8 @@ static int __ip_append_data(struct sock *sk,
		if (copy > length)
		copy = length;

		if (!(rt->dst.dev->features&NETIF_F_SG)) {
		if (!(rt->dst.dev->features&NETIF_F_SG) &&
		skb_tailroom(skb) >= copy) {
		unsigned int off;

		off = skb->len;

net/ipv6/ip6_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1503,7 +1503,8 @@ static int __ip6_append_data(struct sock *sk,
		if (copy > length)
		copy = length;

		if (!(rt->dst.dev->features&NETIF_F_SG)) {
		if (!(rt->dst.dev->features&NETIF_F_SG) &&
		skb_tailroom(skb) >= copy) {
		unsigned int off;

		off = skb->len;