[43/50] Fix oops in vlan and bridging code

Greg KH
2007-09-24T16:41:54Z

[-- Attachment #1: fix-oops-in-vlan-and-bridging-code.patch --]
[-- Type: text/plain, Size: 2796 bytes --]

From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>

commit 8c7b43a2e58baa24002fa2b266d9a5007bc52a40 in mainline

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: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/8021q/vlan_dev.c | 12 +++++++++++-
net/bridge/br_netfilter.c | 12 +++++++-----
2 files changed, 18 insertions(+), 6 deletions(-)

--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -116,12 +116,22 @@ int vlan_skb_recv(struct sk_buff *skb, s
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);

--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -509,8 +509,14 @@ static unsigned int br_nf_pre_routing(un
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(un
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(un
!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)))

--