netdev - skbuff: Fix checksum start check in skb_postpull

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Message-ID: <20151001113407.GA26772@gondor.apana.org.au>
Date:	Thu, 1 Oct 2015 19:34:07 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Mike Galbraith <umgwanakikbuti@...il.com>
Cc:	netdev@...r.kernel.org, pshelar@...ira.com,
	linux-kernel@...r.kernel.org
Subject: skbuff: Fix checksum start check in skb_postpull_rcsum

In skb_postpull_rcsum the skb has already been pulled so we should
be testing whether the checksum start offset is non-negative rather
than how it compares to the length that we have pulled.

Fixes: 6ae459bdaaee ("skbuff: Fix skb checksum flag on skb pull")
Reported-by: Mike Galbraith <umgwanakikbuti@...il.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2b0a30a..4398411 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2708,7 +2708,7 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,
 	if (skb->ip_summed == CHECKSUM_COMPLETE)
 		skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
 	else if (skb->ip_summed == CHECKSUM_PARTIAL &&
-		 skb_checksum_start_offset(skb) <= len)
+		 skb_checksum_start_offset(skb) < 0)
 		skb->ip_summed = CHECKSUM_NONE;
 }
 
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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