From: David Miller on
From: Andrea Shepard <andrea(a)>
Date: Thu, 22 Jul 2010 12:12:35 -0700

> Make pskb_expand_head() check ip_summed to make sure csum_start is really
> csum_start and not csum before adjusting it.
> Signed-off-by: Andrea Shepard <andrea(a)>

Applied, but your email client corrupted tab characters into spaces so
I had to apply your patch by hand.

There is a similar bug in skb_copy_expand() so I fixed that too.

Thanks again.

net: Fix skb_copy_expand() handling of ->csum_start

It should only be adjusted if ip_summed == CHECKSUM_PARTIAL.

Signed-off-by: David S. Miller <davem(a)>
net/core/skbuff.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c699159..ce88293 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -932,7 +932,8 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
copy_skb_header(n, skb);

off = newheadroom - oldheadroom;
- n->csum_start += off;
+ if (n->ip_summed == CHECKSUM_PARTIAL)
+ n->csum_start += off;
n->transport_header += off;
n->network_header += off;

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