set fake_rtable's dst to NULL to avoid kernel Oops.

PATCH Superseded Peter Huang(Peng) 2 participants 3 messages Apr 19, 2012

Subsystems (4)

Networking Network drivers netfilter Ethernet bridge

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Peter Huang(Peng)

author

2012-04-19 02:27 UTC #0 lore raw

PATCH v3 1/1 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.

v3 enrich commit header

v2 added a new flag DST_FAKE_RTABLE to dst_entry struct.

Acked-by Eric Dumazet <[email protected]>

Signed-off-by Peter Huang <[email protected]>

---
 include/linux/netfilter_bridge.h |    8 ++++++++
 include/net/dst.h                |    1 +
 net/bridge/br_forward.c          |    1 +
 net/bridge/br_netfilter.c        |    8 ++------
 4 files changed, 12 insertions(+), 6 deletions(-)

include/linux/netfilter_bridge.h +8 -0

index 0ddd161..51745df 100644
@@ -104,9 +104,17 @@ 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)               (0)
 #endif /* CONFIG_BRIDGE_NETFILTER */
 
 #endif /* __KERNEL__ */

include/net/dst.h +1 -0

index 59c5d18..b094030 100644
@@ -55,6 +55,7 @@ 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

index 61f6534..a2098e3 100644
@@ -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

index dec4f38..d7f49b6 100644
@@ -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;
 }

Stephen Hemminger

2012-04-19 06:46 UTC #1 lore raw

Quoted 5 lines · On Thu, 19 Apr 2012 10:27:01 +0800 "Peter Huang(Peng)"…

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.

Quoted 7 lines

v3 enrich commit header
v2 added a new flag DST_FAKE_RTABLE to dst_entry struct.
Acked-by Eric Dumazet <[email protected]>
Signed-off-by Peter Huang <[email protected]>

I am okay with the contents of the patch but the formatting is all botched. It adds bad indentation and whitespace, please run it through checkpatch.

Peter Huang(Peng)

author

2012-04-19 08:59 UTC #2 lore raw

Quoted 13 lines · Stephen Hemminger

Quoted 10 lines · On Thu, 19 Apr 2012 10:27:01 +0800 "Peter…
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.
v3 enrich commit header
v2 added a new flag DST_FAKE_RTABLE to dst_entry struct.

Quoted 6 lines

Quoted 2 lines
Acked-by Eric Dumazet<[email protected]>
Signed-off-by Peter Huang<[email protected]>
I am okay with the contents of the patch but the formatting is all botched. It adds bad indentation and whitespace, please run it through checkpatch.

Got it, I will send the v4 version of modified format. Thanks!