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Commit a881e963 authored by Peter Huang (Peng)'s avatar Peter Huang (Peng) Committed by David S. Miller
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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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPeter Huang <peter.huangpeng@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4d634ca3

include/linux/netfilter_bridge.h

+9 −0
Original line number Diff line number Diff line
@@ -104,9 +104,18 @@ struct bridge_skb_cb { 
	} daddr;

};



static inline void br_drop_fake_rtable(struct sk_buff *skb)

{

	struct dst_entry *dst = skb_dst(skb);



	if (dst && (dst->flags & DST_FAKE_RTABLE))

		skb_dst_drop(skb);

}



#else

#define nf_bridge_maybe_copy_header(skb)	(0)

#define nf_bridge_pad(skb)			(0)

#define br_drop_fake_rtable(skb)	        do { } while (0)

#endif /* CONFIG_BRIDGE_NETFILTER */



#endif /* __KERNEL__ */

include/net/dst.h

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ struct dst_entry { 
#define DST_NOCACHE		0x0010

#define DST_NOCOUNT		0x0020

#define DST_NOPEER		0x0040

#define DST_FAKE_RTABLE		0x0080



	short			error;

	short			obsolete;

net/bridge/br_forward.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

	}

net/bridge/br_netfilter.c

+2 −6
Original line number Diff line number Diff line
@@ -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;

}