set fake_rtable's dst to NULL to avoid kernel Oops

bridge: set fake_rtable's dst to NULL to avoid kernel Oops

when bridge is deleted before tap/vif device's delete, kernel may
encounter an oops because of NULL reference to fake_rtable's dst.
Set fake_rtable's dst to NULL before sending packets out can solve
this problem.

v4 reformat, change br_drop_fake_rtable(skb) to {}

v3 enrich commit header

v2 introducing new flag DST_FAKE_RTABLE to dst_entry struct.

[ Use "do { } while (0)" for nop br_drop_fake_rtable()
  implementation -DaveM ]

Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: Peter Huang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Peter Huang (Peng) 2012-04-19 20:12:51 +00:00 • committed by David S. Miller
commit a881e963c7
4 changed files with 13 additions and 6 deletions

View file

@ -47,6 +47,7 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
kfree_skb(skb);
} else {
skb_push(skb, ETH_HLEN);
br_drop_fake_rtable(skb);
dev_queue_xmit(skb);
}

View file

@ -156,7 +156,7 @@ void br_netfilter_rtable_init(struct net_bridge *br)
rt->dst.dev = br->dev;
rt->dst.path = &rt->dst;
dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
rt->dst.flags = DST_NOXFRM | DST_NOPEER;
rt->dst.flags = DST_NOXFRM | DST_NOPEER | DST_FAKE_RTABLE;
rt->dst.ops = &fake_dst_ops;
}
@ -694,11 +694,7 @@ static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct rtable *rt = skb_rtable(skb);
if (rt && rt == bridge_parent_rtable(in))
skb_dst_drop(skb);
br_drop_fake_rtable(skb);
return NF_ACCEPT;
}