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[NETFILTER]: ipt_REJECT: fix memory corruption

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On devices with hard_header_len > LL_MAX_HEADER ip_route_me_harder()
reallocates the skb, leading to memory corruption when using the stale
tcph pointer to update the checksum.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2006-11-28 20:10:21 -08:00 committed by David S. Miller
parent 2e47c264a2
commit af443b6d90
1 changed files with 9 additions and 7 deletions
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16
net/ipv4/netfilter/ipt_REJECT.c
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@ -114,6 +114,14 @@ static void send_reset(struct sk_buff *oldskb, int hook)
tcph->window = 0;
tcph->urg_ptr = 0;
/* Adjust TCP checksum */
tcph->check = 0;
tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr),
nskb->nh.iph->saddr,
nskb->nh.iph->daddr,
csum_partial((char *)tcph,
sizeof(struct tcphdr), 0));
/* Set DF, id = 0 */
nskb->nh.iph->frag_off = htons(IP_DF);
nskb->nh.iph->id = 0;
@ -129,14 +137,8 @@ static void send_reset(struct sk_buff *oldskb, int hook)
if (ip_route_me_harder(&nskb, addr_type))
goto free_nskb;
/* Adjust TCP checksum */
nskb->ip_summed = CHECKSUM_NONE;
tcph->check = 0;
tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr),
nskb->nh.iph->saddr,
nskb->nh.iph->daddr,
csum_partial((char *)tcph,
sizeof(struct tcphdr), 0));
/* Adjust IP TTL */
nskb->nh.iph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);