[IPV4] ipmr: ip multicast route bug fix.
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>
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 9ccacf5..85893ee 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1578,6 +1578,7 @@
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 @@
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;
}