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arp: fix possible crash in arp_rcv() 

We should call skb_share_check() before pskb_may_pull(), or we
can crash in pskb_expand_head()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-02-08 18:48:21 +00:00 committed by David S. Miller
parent 839c8cc32b
commit 044453b3ef
1 changed files with 11 additions and 10 deletions
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21
net/ipv4/arp.c
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@ -928,24 +928,25 @@ static void parp_redo(struct sk_buff *skb)
static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
struct arphdr *arp;
const struct arphdr *arp;
if (dev->flags & IFF_NOARP ||
skb->pkt_type == PACKET_OTHERHOST ||
skb->pkt_type == PACKET_LOOPBACK)
goto freeskb;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
goto out_of_mem;
/* ARP header, plus 2 device addresses, plus 2 IP addresses. */
if (!pskb_may_pull(skb, arp_hdr_len(dev)))
goto freeskb;
arp = arp_hdr(skb);
if (arp->ar_hln != dev->addr_len ||
dev->flags & IFF_NOARP ||
skb->pkt_type == PACKET_OTHERHOST ||
skb->pkt_type == PACKET_LOOPBACK ||
arp->ar_pln != 4)
if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
goto freeskb;
skb = skb_share_check(skb, GFP_ATOMIC);
if (skb == NULL)
goto out_of_mem;
memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, skb, dev, NULL, arp_process);