From 2ef22bd08dcff6a8d761829647e5eb321576a83a Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Thu, 17 May 2018 13:13:29 -0400 Subject: [PATCH] net: test tailroom before appending to linear skb [ Upstream commit 113f99c3358564a0647d444c2ae34e8b1abfd5b9 ] 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: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Eric Dumazet Signed-off-by: Willem de Bruijn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ip_output.c | 3 ++- net/ipv6/ip6_output.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 2c3c1a223df4..3b1f3bc8becb 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1076,7 +1076,8 @@ 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; diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 58a6eeeacbf7..e8560031a0be 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1545,7 +1545,8 @@ 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; -- 2.20.1