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Commit e7c243c9 authored by Evgeniy Polyakov's avatar Evgeniy Polyakov Committed by David S. Miller
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[VLAN/BRIDGE]: Fix "skb_pull_rcsum - Fatal exception in interrupt" 



I tried to preserve bridging code as it was before, but logic is quite
strange - I think we should free skb on error, since it is already
unshared and thus will just leak.

Herbert Xu states:

> +	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
> +		goto out;

If this happens it'll be a double-free on skb since we'll
return NF_DROP which makes the caller free it too.

We could return NF_STOLEN to prevent that but I'm not sure
whether that's correct netfilter semantics.  Patrick, could
you please make a call on this?

Patrick McHardy states:

NF_STOLEN should work fine here.

Signed-off-by: default avatarEvgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7c8347a9

net/8021q/vlan_dev.c

+11 −1
Original line number Diff line number Diff line
@@ -116,12 +116,22 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev, 
		  struct packet_type* ptype, struct net_device *orig_dev)

{

	unsigned char *rawp = NULL;

	struct vlan_hdr *vhdr = (struct vlan_hdr *)(skb->data);

	struct vlan_hdr *vhdr;

	unsigned short vid;

	struct net_device_stats *stats;

	unsigned short vlan_TCI;

	__be16 proto;



	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)

		return -1;



	if (unlikely(!pskb_may_pull(skb, VLAN_HLEN))) {

		kfree_skb(skb);

		return -1;

	}



	vhdr = (struct vlan_hdr *)(skb->data);



	/* vlan_TCI = ntohs(get_unaligned(&vhdr->h_vlan_TCI)); */

	vlan_TCI = ntohs(vhdr->h_vlan_TCI);

net/bridge/br_netfilter.c

+7 −5
Original line number Diff line number Diff line
@@ -509,8 +509,14 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb, 
				      int (*okfn)(struct sk_buff *))

{

	struct iphdr *iph;

	__u32 len;

	struct sk_buff *skb = *pskb;

	__u32 len = nf_bridge_encap_header_len(skb);



	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)

		return NF_STOLEN;



	if (unlikely(!pskb_may_pull(skb, len)))

		goto out;



	if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||

	    IS_PPPOE_IPV6(skb)) {
@@ -518,8 +524,6 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb, 
		if (!brnf_call_ip6tables)

			return NF_ACCEPT;

#endif

		if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)

			goto out;

		nf_bridge_pull_encap_header_rcsum(skb);

		return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);

	}
@@ -532,8 +536,6 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb, 
	    !IS_PPPOE_IP(skb))

		return NF_ACCEPT;



	if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)

		goto out;

	nf_bridge_pull_encap_header_rcsum(skb);



	if (!pskb_may_pull(skb, sizeof(struct iphdr)))