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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: 1da177e4c3 ("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>
zero-colors
Willem de Bruijn 2018-05-17 13:13:29 -04:00 committed by David S. Miller
parent 374edea4aa
commit 113f99c335
2 changed files with 4 additions and 2 deletions

View File

@ -1045,7 +1045,8 @@ alloc_new_skb:
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;

View File

@ -1503,7 +1503,8 @@ alloc_new_skb:
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;