netdev - [PATCH] netpoll: fix incorrect access to skb data in __netpoll

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Date:	Fri, 26 Aug 2011 18:26:15 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>
Subject: [PATCH] netpoll: fix incorrect access to skb data in __netpoll_rx

__netpoll_rx() doesnt properly handle skbs with small header

pskb_may_pull() or pskb_trim_rcsum() can change skb->data, we must
reload it.

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
 net/core/netpoll.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index adf84dd..5262251 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -558,13 +558,14 @@ int __netpoll_rx(struct sk_buff *skb)
 	if (skb_shared(skb))
 		goto out;
 
-	iph = (struct iphdr *)skb->data;
 	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 		goto out;
+	iph = (struct iphdr *)skb->data;
 	if (iph->ihl < 5 || iph->version != 4)
 		goto out;
 	if (!pskb_may_pull(skb, iph->ihl*4))
 		goto out;
+	iph = (struct iphdr *)skb->data;
 	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
 		goto out;
 
@@ -579,6 +580,7 @@ int __netpoll_rx(struct sk_buff *skb)
 	if (pskb_trim_rcsum(skb, len))
 		goto out;
 
+	iph = (struct iphdr *)skb->data;
 	if (iph->protocol != IPPROTO_UDP)
 		goto out;
 


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