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udp: Fix potential wrong ip_hdr(skb) pointers 

Like the UDP header fix, pskb_may_pull() can potentially
alter the SKB buffer.  Thus the saddr and daddr, pointers
may point to the old skb->data buffer.

I haven't seen corruptions, as its only seen if the old
skb->data buffer were reallocated by another user and
written into very quickly (or poison'd by SLAB debugging).

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2009-02-06 01:59:12 -08:00 committed by David S. Miller
parent efc683fc2a
commit 2783ef2312
1 changed files with 4 additions and 2 deletions
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6
net/ipv4/udp.c
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@ -1234,8 +1234,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
struct udphdr *uh;
unsigned short ulen;
struct rtable *rt = (struct rtable*)skb->dst;
__be32 saddr = ip_hdr(skb)->saddr;
__be32 daddr = ip_hdr(skb)->daddr;
__be32 saddr, daddr;
struct net *net = dev_net(skb->dev);
/*
@ -1259,6 +1258,9 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
if (udp4_csum_init(skb, uh, proto))
goto csum_error;
saddr = ip_hdr(skb)->saddr;
daddr = ip_hdr(skb)->daddr;
if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
return __udp4_lib_mcast_deliver(net, skb, uh,
saddr, daddr, udptable);