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[IPV4] ipmr: ip multicast route bug fix.

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IP multicast route code was reusing an skb which causes use after free
and double free.

From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>

Note, it is real skb_clone(), not alloc_skb(). Equeued skb contains
the whole half-prepared netlink message plus room for the rest.
It could be also skb_copy(), if we want to be puristic about mangling
cloned data, but original copy is really not going to be used.  

Acked-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexey Kuznetsov 2006-07-25 16:45:12 -07:00 committed by David S. Miller
parent b6e77a5346
commit 7228749092
1 changed files with 13 additions and 6 deletions
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19
net/ipv4/ipmr.c
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@ -1578,6 +1578,7 @@ int ipmr_get_route(struct sk_buff *skb, struct rtmsg *rtm, int nowait)
cache = ipmr_cache_find(rt->rt_src, rt->rt_dst);
if (cache==NULL) {
struct sk_buff *skb2;
struct net_device *dev;
int vif;
@ -1591,12 +1592,18 @@ int ipmr_get_route(struct sk_buff *skb, struct rtmsg *rtm, int nowait)
read_unlock(&mrt_lock);
return -ENODEV;
}
skb->nh.raw = skb_push(skb, sizeof(struct iphdr));
skb->nh.iph->ihl = sizeof(struct iphdr)>>2;
skb->nh.iph->saddr = rt->rt_src;
skb->nh.iph->daddr = rt->rt_dst;
skb->nh.iph->version = 0;
err = ipmr_cache_unresolved(vif, skb);
skb2 = skb_clone(skb, GFP_ATOMIC);
if (!skb2) {
read_unlock(&mrt_lock);
return -ENOMEM;
}
skb2->nh.raw = skb_push(skb2, sizeof(struct iphdr));
skb2->nh.iph->ihl = sizeof(struct iphdr)>>2;
skb2->nh.iph->saddr = rt->rt_src;
skb2->nh.iph->daddr = rt->rt_dst;
skb2->nh.iph->version = 0;
err = ipmr_cache_unresolved(vif, skb2);
read_unlock(&mrt_lock);
return err;
}