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Date: Fri, 06 Jul 2012 22:19:54 +0800
From: Lin Ming <mlin@...pku.edu.cn>
To: Massimo Cetra <ctrix+debianbugs@...ynet.it>,
Eric Dumazet <eric.dumazet@...il.com>
Cc: netdev@...r.kernel.org, Stephen Hemminger <shemminger@...tta.com>,
"David S. Miller" <davem@...emloft.net>,
Julian Anastasov <ja@....bg>
Subject: [RFC PATCH] bridge: netfilter: fix skb->nf_bridge NULL panic in
br_nf_forward_finish
I can reproduce similiar panic with 3.5-rc5 kernel as Massimo reported at:
http://marc.info/?l=linux-netdev&m=134089242113979&w=2
The steps to reproduce as follow,
1. On Host1, setup brige br0(192.168.1.106)
2. Boot a kvm guest(192.168.1.105) on Host1 and start httpd
3. Start IPVS service on Host1
ipvsadm -A -t 192.168.1.106:80 -s rr
ipvsadm -a -t 192.168.1.106:80 -r 192.168.1.105:80 -m
4. Run apache benchmark on Host2(192.168.1.101)
ab -n 1000 http://192.168.1.106/
The panic happened in br_nf_forward_finish because skb->nf_bridge is NULL.
skb->nf_bridge is set to NULL in ip_vs_reply4 hook.
br_nf_forward_ip():
NF_HOOK(pf, NF_INET_FORWARD, skb, brnf_get_logical_dev(skb, in), parent,
br_nf_forward_finish);
This calls IPVS hook ip_vs_reply4.
ip_vs_reply4
ip_vs_out
handle_response
ip_vs_notrack
nf_reset()
{
skb->nf_bridge = NULL;
}
This patch added skb->nf_bridge check in br_nf_forward_finish and the panic gone.
But I am really not sure if this is the right fix.
Please help to review.
The panic log attached.
[ 579.781508] BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
[ 579.781669] IP: [<ffffffff817b1ca5>] br_nf_forward_finish+0x58/0x112
[ 579.781792] PGD 218f9067 PUD 0
[ 579.781865] Oops: 0000 [#1] SMP
[ 579.781945] CPU 0
[ 579.781983] Modules linked in:
[ 579.782047]
[ 579.782080]
[ 579.782114] Pid: 4644, comm: qemu Tainted: G W 3.5.0-rc5-00006-g95e69f9 #282 Hewlett-Packard /30E8
[ 579.782300] RIP: 0010:[<ffffffff817b1ca5>] [<ffffffff817b1ca5>] br_nf_forward_finish+0x58/0x112
[ 579.782455] RSP: 0018:ffff88007b003a98 EFLAGS: 00010287
[ 579.782541] RAX: 0000000000000008 RBX: ffff8800762ead00 RCX: 000000000001670a
[ 579.782653] RDX: 0000000000000000 RSI: 000000000000000a RDI: ffff8800762ead00
[ 579.782845] RBP: ffff88007b003ac8 R08: 0000000000016630 R09: ffff88007b003a90
[ 579.782957] R10: ffff88007b0038e8 R11: ffff88002da37540 R12: ffff88002da01a02
[ 579.783066] R13: ffff88002da01a80 R14: ffff88002d83c000 R15: ffff88002d82a000
[ 579.783177] FS: 0000000000000000(0000) GS:ffff88007b000000(0063) knlGS:00000000f62d1b70
[ 579.783306] CS: 0010 DS: 002b ES: 002b CR0: 000000008005003b
[ 579.783395] CR2: 0000000000000004 CR3: 00000000218fe000 CR4: 00000000000027f0
[ 579.783505] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 579.783684] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 579.783795] Process qemu (pid: 4644, threadinfo ffff880021b20000, task ffff880021aba760)
[ 579.783919] Stack:
[ 579.783959] ffff88007693cedc ffff8800762ead00 ffff88002da01a02 ffff8800762ead00
[ 579.784110] ffff88002da01a02 ffff88002da01a80 ffff88007b003b18 ffffffff817b26c7
[ 579.784260] ffff880080000000 ffffffff81ef59f0 ffff8800762ead00 ffffffff81ef58b0
[ 579.784477] Call Trace:
[ 579.784523] <IRQ>
[ 579.784562]
[ 579.784603] [<ffffffff817b26c7>] br_nf_forward_ip+0x275/0x2c8
[ 579.784707] [<ffffffff81704b58>] nf_iterate+0x47/0x7d
[ 579.784797] [<ffffffff817ac32e>] ? br_dev_queue_push_xmit+0xae/0xae
[ 579.784906] [<ffffffff81704bfb>] nf_hook_slow+0x6d/0x102
[ 579.784995] [<ffffffff817ac32e>] ? br_dev_queue_push_xmit+0xae/0xae
[ 579.785175] [<ffffffff8187fa95>] ? _raw_write_unlock_bh+0x19/0x1b
[ 579.785179] [<ffffffff817ac417>] __br_forward+0x97/0xa2
[ 579.785179] [<ffffffff817ad366>] br_handle_frame_finish+0x1a6/0x257
[ 579.785179] [<ffffffff817b2386>] br_nf_pre_routing_finish+0x26d/0x2cb
[ 579.785179] [<ffffffff817b2cf0>] br_nf_pre_routing+0x55d/0x5c1
[ 579.785179] [<ffffffff81704b58>] nf_iterate+0x47/0x7d
[ 579.785179] [<ffffffff817ad1c0>] ? br_handle_local_finish+0x44/0x44
[ 579.785179] [<ffffffff81704bfb>] nf_hook_slow+0x6d/0x102
[ 579.785179] [<ffffffff817ad1c0>] ? br_handle_local_finish+0x44/0x44
[ 579.785179] [<ffffffff81551525>] ? sky2_poll+0xb35/0xb54
[ 579.785179] [<ffffffff817ad62a>] br_handle_frame+0x213/0x229
[ 579.785179] [<ffffffff817ad417>] ? br_handle_frame_finish+0x257/0x257
[ 579.785179] [<ffffffff816e3b47>] __netif_receive_skb+0x2b4/0x3f1
[ 579.785179] [<ffffffff816e69fc>] process_backlog+0x99/0x1e2
[ 579.785179] [<ffffffff816e6800>] net_rx_action+0xdf/0x242
[ 579.785179] [<ffffffff8107e8a8>] __do_softirq+0xc1/0x1e0
[ 579.785179] [<ffffffff8135a5ba>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[ 579.785179] [<ffffffff8188812c>] call_softirq+0x1c/0x30
Signed-off-by: Lin Ming <mlin@...pku.edu.cn>
---
net/bridge/br_netfilter.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index e41456b..10da415 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -719,7 +719,7 @@ static int br_nf_forward_finish(struct sk_buff *skb)
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
struct net_device *in;
- if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
+ if (!IS_ARP(skb) && !IS_VLAN_ARP(skb) && nf_bridge) {
in = nf_bridge->physindev;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
--
1.7.2.5
--
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