diff mbox series

[net,v2] net: test tailroom before appending to linear skb

Message ID 20180517171329.201710-1-willemdebruijn.kernel@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show
Series [net,v2] net: test tailroom before appending to linear skb | expand

Commit Message

Willem de Bruijn May 17, 2018, 5:13 p.m. UTC 
From: Willem de Bruijn <willemb@google.com>

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 <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>

---

v2: fix ipv4 boundary condition
---
 net/ipv4/ip_output.c  | 3 ++-
 net/ipv6/ip6_output.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

Comments

Eric Dumazet May 17, 2018, 5:18 p.m. UTC | #1 
On 05/17/2018 10:13 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@google.com>
> 
> 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 <edumazet@google.com>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> 

Reviewed-by: Eric Dumazet <edumazet@google.com>
David Miller May 17, 2018, 9:07 p.m. UTC | #2 
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Thu, 17 May 2018 13:13:29 -0400

> From: Willem de Bruijn <willemb@google.com>
> 
> 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 <edumazet@google.com>
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> 
> ---
> 
> v2: fix ipv4 boundary condition

Applied and queued up for -stable, thanks Willem.
diff mbox series

Patch

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 83c73bab2c3d..d54abc097800 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -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;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 2e891d2c30ef..7b6d1689087b 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -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;