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Commit 2783ef23 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
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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: default avatarJesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent efc683fc

net/ipv4/udp.c

+4 −2
Original line number Diff line number Diff line
@@ -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);