[patch 10/74] gso: Stop fraglists from escaping

[Greg KH]

2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 278b2513f76161a9cf1ebddd620dc9d1714fe573 ]

As it stands skb fraglists can get past the check in dev_queue_xmit
if the skb is marked as GSO.  In particular, if the packet doesn't
have the proper checksums for GSO, but can otherwise be handled by
the underlying device, we will not perform the fraglist check on it
at all.

If the underlying device cannot handle fraglists, then this will
break.

The fix is as simple as moving the fraglist check from the device
check into skb_gso_ok.

This has caused crashes with Xen when used together with GRO which
can generate GSO packets with fraglists.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 include/linux/netdevice.h |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1856,15 +1856,14 @@ static inline int net_gso_ok(int feature
 
 static inline int skb_gso_ok(struct sk_buff *skb, int features)
 {
-	return net_gso_ok(features, skb_shinfo(skb)->gso_type);
+	return net_gso_ok(features, skb_shinfo(skb)->gso_type) &&
+	       (!skb_shinfo(skb)->frag_list || (features & NETIF_F_FRAGLIST));
 }
 
 static inline int netif_needs_gso(struct net_device *dev, struct sk_buff *skb)
 {
 	return skb_is_gso(skb) &&
 	       (!skb_gso_ok(skb, dev->features) ||
-	        (skb_shinfo(skb)->frag_list &&
-	         !(dev->features & NETIF_F_FRAGLIST)) ||
 		unlikely(skb->ip_summed != CHECKSUM_PARTIAL));
 }
 


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