netdev - Re: Fw: [Bug 75571] New: using tc action mirred results BUG at net/core/skbuff.c:119

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Date:	Tue, 6 May 2014 15:30:48 -0700
From:	Cong Wang <cwang@...pensource.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	netdev <netdev@...r.kernel.org>, d77190@...l.ru,
	Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: Fw: [Bug 75571] New: using tc action mirred results BUG at net/core/skbuff.c:119

On Tue, May 6, 2014 at 8:16 AM, Stephen Hemminger
<stephen@...workplumber.org> wrote:
> Hello!
> Got this bug while setting large shaper ruleset (about 4k hash rules) on mirred
> ifb interface at boot time:
> Attached archive consists of used shaper scripts.
>
> [   19.355181] ------------[ cut here ]------------
> [   19.356148] kernel BUG at net/core/skbuff.c:119!
> [   19.356148] invalid opcode: 0000 [#1] SMP
> [   19.356148] Modules linked in: pppoe pppox ppp_generic slhc sch_sfq sch_htb
> act_mirred cls_u32 sch_ingress ipt_REJECT ext4 jbd2 ipt_MASQUERADE xt_multiport
> xt_rateest xt_RATEEST xt_layer7 xt_HL xt_TPROXY nf_tproxy_core xt_set
> xt_connmark ipt_DF ipt_ULOG xt_socket ip6_tables nf_defrag_ipv6 xt_mark
> xt_conntrack xt_TCPMSS xt_tcpudp xt_DSCP xt_dscp iptable_raw iptable_mangle
> iptable_nat nf_nat nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 iptable_filter
> ip_tables x_tables ip_set_hash_net ip_set nfnetlink cpufreq_ondemand
> acpi_cpufreq freq_table processor coretemp mperf ipip hwmon macvlan ifb tun
> ipmi_watchdog ipmi_si ipmi_msghandler pcspkr
> [   19.356148]
> [   19.356148] Pid: 2305, comm: openvpn Not tainted 3.2.58 #1 Intel Corporation
> S3210SH/S3210SH
> [   19.356148] EIP: 0060:[<c05cb9e4>] EFLAGS: 00210296 CPU: 0
> [   19.356148] EIP is at skb_push+0x84/0x90
> [   19.356148] EAX: 0000008b EBX: ef7a7a8e ECX: 00000000 EDX: fffe7ddb
> [   19.356148] ESI: f1af8800 EDI: ebc1e840 EBP: f540be24 ESP: f540bdf8
> [   19.356148]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> [   19.356148] Process openvpn (pid: 2305, ti=f540a000 task=f568b190
> task.ti=f1b42000)
> [   19.356148] Stack:
> [   19.356148]  c0988ec4 f9ace566 000000ce 00000094 ef7a7a00 ef7a79c0 ef7a7a8e
> ef7a7b40
> [   19.356148]  f1af8800 f157ed00 ebc1e600 f540be48 f9ace566 f140c800 00000000
> f2790800
> [   19.356148]  00000001 f9ace450 f1459220 ebc1e600 f540be60 c05f0cff f540bf1c
> 00000000
> [   19.356148] Call Trace:
> [   19.356148]  [<f9ace566>] ? tcf_mirred+0x116/0x15c [act_mirred]
> [   19.356148]  [<f9ace566>] tcf_mirred+0x116/0x15c [act_mirred]
> [   19.356148]  [<f9ace450>] ? tcf_mirred_dump+0x110/0x110 [act_mirred]
> [   19.356148]  [<c05f0cff>] tcf_action_exec+0x3f/0x80
> [   19.356148]  [<f9ac70d2>] u32_classify+0x212/0x374 [cls_u32]
> [   19.356148]  [<f83e59e6>] ? ipip_rcv+0x136/0x220 [ipip]
> [   19.356148]  [<c05f779a>] ? nf_hook_slow+0x5a/0x110
> [   19.356148]  [<c063c5a3>] ? tunnel4_rcv+0x33/0x90
> [   19.356148]  [<c05fe0bf>] ? ip_local_deliver_finish+0x9f/0x230
> [   19.356148]  [<c05ed981>] tc_classify_compat+0x31/0x70
> [   19.356148]  [<c05ee8c4>] tc_classify+0x44/0xb0
> [   19.356148]  [<f9abe0f1>] ingress_enqueue+0x21/0x80 [sch_ingress]
> [   19.356148]  [<c05d2740>] __netif_receive_skb+0x2e0/0x4e0
> [   19.356148]  [<c05d2a0a>] process_backlog+0xca/0x1a0
> [   19.356148]  [<c05d4929>] net_rx_action+0xc9/0x1c0
> [   19.356148]  [<c013e95b>] __do_softirq+0x7b/0x110
> [   19.356148]  [<c013e8e0>] ? irq_enter+0x70/0x70
> [   19.356148]  [<c013e8e0>] ? irq_enter+0x70/0x70
> [   19.356148]  <IRQ>
> [   19.356148]  [<c05d4b30>] ? netif_rx_ni+0x20/0x30
> [   19.356148]  [<f836e959>] ? tun_get_user+0x1a9/0x3e0 [tun]
> [   19.356148]  [<f836ec2e>] ? tun_chr_aio_write+0x6e/0xb0 [tun]
> [   19.356148]  [<c01bb3bc>] ? do_sync_write+0xac/0xf0
> [   19.356148]  [<c010b487>] ? init_fpu+0xd7/0x160
> [   19.356148]  [<c0123b30>] ? mm_fault_error+0x130/0x130
> [   19.356148]  [<c01bbeca>] ? vfs_write+0x9a/0x170
> [   19.673799]  [<c01bb310>] ? do_sync_readv_writev+0xe0/0xe0
> [   19.673799]  [<c01bc06d>] ? sys_write+0x3d/0x70
> [   19.673799]  [<c06d291c>] ? sysenter_do_call+0x12/0x2c
> [   19.673799] Code: 5c 24 18 8b 88 a8 00 00 00 89 54 24 0c 89 4c 24 10 8b 40
> 50 c7 04 24 c4 8e 98 c0 89 44 24 08 8b 45 04 89 44 24 04 e8 e9 3b 10 00 <0f> 0b
> eb fe 90 8d b4 26 00 00 00 00 55 89 e5 56 53 83 ec 24 8b
> [   19.673799] EIP: [<c05cb9e4>] skb_push+0x84/0x90 SS:ESP 0068:f540bdf8
> [   19.726460] ---[ end trace c5c43cec4bd0fcd8 ]---
> [   19.731801] Kernel panic - not syncing: Fatal exception in interrupt
>

Hmm, looks like we pushed wrong header size here. tcf_mirred_init()
checks if we could push hard header by checking the type of the target device,
while in tcf_mirred() we push the ->hard_header_len of the source device
where this skb is received. I am not sure at all.

Jamal, does the following patch make any sense for you?

---
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 4f912c0..8199540 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -157,7 +157,7 @@ static int tcf_mirred(struct sk_buff *skb, const
struct tc_action *a,

        if (!(at & AT_EGRESS)) {
                if (m->tcfm_ok_push)
-                       skb_push(skb2, skb2->dev->hard_header_len);
+                       skb_push(skb2, dev->hard_header_len);
        }

        /* mirror is always swallowed */
--
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