PANIC at net/xfrm/xfrm_output.c:125 (3.9.4)

[Chris Boot]

Hi folks,

I have a re-purposed Watchguard Firebox running Debian GNU/Linux with a
self-built vanilla 3.9.4 kernel. I have an IPsec tunnel up to a remote
router through which I was passing a fair bit of traffic when I hit the
following panic:

[486832.949560] BUG: unable to handle kernel NULL pointer dereference at
00000010
[486832.953431] IP: [<c12a4dd0>] xfrm_output_resume+0x61/0x29f
[486832.953431] *pde = 00000000
[486832.953431] Oops: 0000 [#1]
[486832.953431] Modules linked in: xt_realm xt_nat authenc esp4
xfrm4_mode_tunnel tun ip6table_nat nf_nat_ipv6 sch_fq_codel xt_statistic
xt_CT xt_LOG xt_connlimit xt_recent xt_time xt_TCPMSS xt_sctp
ip6t_REJECT pppoe deflate zlib_deflate pppox ctr twofish_generic
twofish_i586 twofish_common camellia_generic serpent_sse2_i586 xts
serpent_generic lrw gf128mul glue_helper ablk_helper cryptd
blowfish_generic blowfish_common cast5_generic cast_common des_generic
cbc xcbc rmd160 sha512_generic sha256_generic sha1_generic hmac
crypto_null af_key xfrm_algo xt_comment xt_addrtype xt_policy
ip_set_hash_ip ipt_ULOG ipt_REJECT ipt_MASQUERADE ipt_ECN ipt_CLUSTERIP
ipt_ah act_police cls_basic cls_flow cls_fw cls_u32 sch_tbf sch_prio
sch_htb sch_hfsc sch_ingress sch_sfq xt_set ip_set nf_nat_tftp
nf_nat_snmp_basic nf_conntrack_snmp nf_nat_sip nf_nat_pptp
nf_nat_proto_gre nf_nat_irc nf_nat_h323 nf_nat_ftp nf_nat_amanda ts_kmp
nf_conntrack_amanda nf_conntrack_sane nf_conntrack_tftp nf_conntrack_sip
nf_conntrack_proto_udplite nf_conntrack_proto_sctp nf_conntrack_pptp
nf_conntrack_proto_gre nf_conntrack_netlink nf_conntrack_netbios_ns
nf_conntrack_broadcast nf_conntrack_irc nf_conntrack_h323
nf_conntrack_ftp xt_TPROXY nf_tproxy_core xt_tcpmss xt_pkttype
xt_physdev xt_owner xt_NFQUEUE xt_NFLOG nfnetlink_log xt_multiport
xt_mark xt_mac xt_limit xt_length xt_iprange xt_helper xt_hashlimit
xt_DSCP xt_dscp xt_dccp xt_connmark xt_CLASSIFY xt_AUDIT xt_state
nfnetlink bridge 8021q garp stp mrp llc ppp_generic slhc
nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_mangle ip6table_raw
ip6table_filter ip6_tables xt_tcpudp xt_conntrack iptable_mangle
iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat
nf_conntrack iptable_raw iptable_filter ip_tables x_tables w83627hf
hwmon_vid loop iTCO_wdt iTCO_vendor_support evdev snd_pcm snd_page_alloc
snd_timer snd soundcore acpi_cpufreq mperf processor pcspkr serio_raw
drm_kms_helper lpc_ich i2c_i801 of_i2c drm rng_core thermal_sys
i2c_algo_bit ehci_pci i2c_core ext4 crc16 jbd2 mbcache dm_mod sg sd_mod
crc_t10dif ata_generic ata_piix uhci_hcd ehci_hcd libata microcode
scsi_mod skge sky2 usbcore usb_common
[486832.953431] Pid: 0, comm: swapper Not tainted 3.9.4-1-bootc #1
[486832.953431] EIP: 0060:[<c12a4dd0>] EFLAGS: 00210246 CPU: 0
[486832.953431] EIP is at xfrm_output_resume+0x61/0x29f
[486832.953431] EAX: 00000000 EBX: f3fbc100 ECX: f77f1288 EDX: f6130200
[486832.953431] ESI: 00000016 EDI: 00000000 EBP: f70b3c00 ESP: c1407c44
[486832.953431]  DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
[486832.953431] CR0: 8005003b CR2: 00000010 CR3: 37247000 CR4: 000007d0
[486832.953431] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[486832.953431] DR6: ffff0ff0 DR7: 00000400
[486832.953431] Process swapper (pid: 0, ti=c1406000 task=c1413490
task.ti=c1406000)
[486832.953431] Stack:
[486832.953431]  c129d44f 80000000 00000002 c1457254 f3fbc100 c129d44f
00000000 00000008
[486832.953431]  c129d49e 00000000 f4524000 c129d44f 80000000 00000000
f3fbc100 c1268b49
[486832.953431]  f3fbc100 f127604e c12678c3 00000000 f7123000 c1267685
c1457f8c c1456b80
[486832.953431] Call Trace:
[486832.953431]  [<c129d44f>] ? xfrm4_extract_output+0x94/0x94
[486832.953431]  [<c129d44f>] ? xfrm4_extract_output+0x94/0x94
[486832.953431]  [<c129d49e>] ? xfrm4_output+0x2c/0x6a
[486832.953431]  [<c129d44f>] ? xfrm4_extract_output+0x94/0x94
[486832.953431]  [<c1268b49>] ? ip_forward_finish+0x59/0x5c
[486832.953431]  [<c12678c3>] ? ip_rcv_finish+0x23e/0x274
[486832.953431]  [<c1267685>] ? pskb_may_pull+0x2d/0x2d
[486832.953431]  [<c1246890>] ? __netif_receive_skb_core+0x39d/0x406
[486832.953431]  [<f849557f>] ? br_handle_frame_finish+0x22c/0x264 [bridge]
[486832.953431]  [<c1246a16>] ? process_backlog+0xd0/0xd0
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<f8499310>] ? NF_HOOK_THRESH+0x1d/0x4c [bridge]
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<f849983e>] ? br_nf_pre_routing_finish+0x1c8/0x1d2
[bridge]
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<c12635d1>] ? nf_hook_slow+0x52/0xed
[486832.953431]  [<f8499676>] ? nf_bridge_alloc.isra.18+0x32/0x32 [bridge]
[486832.953431]  [<f8499676>] ? nf_bridge_alloc.isra.18+0x32/0x32 [bridge]
[486832.953431]  [<f8499310>] ? NF_HOOK_THRESH+0x1d/0x4c [bridge]
[486832.953431]  [<f8499676>] ? nf_bridge_alloc.isra.18+0x32/0x32 [bridge]
[486832.953431]  [<f849a1c0>] ? br_nf_pre_routing+0x32c/0x33f [bridge]
[486832.953431]  [<f8499676>] ? nf_bridge_alloc.isra.18+0x32/0x32 [bridge]
[486832.953431]  [<c1263552>] ? nf_iterate+0x3c/0x69
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<c12635d1>] ? nf_hook_slow+0x52/0xed
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<f84952fa>] ? nf_hook_thresh.constprop.10+0x36/0x42
[bridge]
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<f8495746>] ? br_handle_frame+0x18f/0x1b5 [bridge]
[486832.953431]  [<f8495353>] ? br_handle_local_finish+0x4d/0x4d [bridge]
[486832.953431]  [<f84955b7>] ? br_handle_frame_finish+0x264/0x264 [bridge]
[486832.953431]  [<c12467a8>] ? __netif_receive_skb_core+0x2b5/0x406
[486832.953431]  [<c1051a58>] ? __getnstimeofday+0x17/0x52
[486832.953431]  [<c1051a00>] ? get_monotonic_boottime+0x73/0x92
[486832.953431]  [<c124704f>] ? napi_gro_receive+0x2e/0x69
[486832.953431]  [<c10053d8>] ? __stop_machine.isra.0.constprop.1+0x27/0x27
[486832.953431]  [<f80792d7>] ? sky2_poll+0x6d8/0x8f3 [sky2]
[486832.953431]  [<c1006058>] ? native_sched_clock+0x40/0x98
[486832.953431]  [<c1006058>] ? native_sched_clock+0x40/0x98
[486832.953431]  [<c1005962>] ? paravirt_sched_clock+0x8/0xb
[486832.953431]  [<c1006058>] ? native_sched_clock+0x40/0x98
[486832.953431]  [<c1246bbf>] ? net_rx_action+0x6e/0x180
[486832.953431]  [<c1005962>] ? paravirt_sched_clock+0x8/0xb
[486832.953431]  [<c102ca5a>] ? __do_softirq+0xa5/0x19e
[486832.953431]  [<c102cbfa>] ? irq_exit+0x36/0x69
[486832.953431]  [<c100326b>] ? do_IRQ+0x6e/0x81
[486832.953431]  [<c12e4cf3>] ? common_interrupt+0x33/0x38
[486832.953431]  [<c101df1b>] ? native_safe_halt+0x2/0x3
[486832.953431]  [<c1006b2f>] ? default_idle+0x23/0x3e
[486832.953431]  [<c10070cd>] ? cpu_idle+0x75/0x8f
[486832.953431]  [<c145996b>] ? start_kernel+0x34e/0x353
[486832.953431]  [<c1459465>] ? repair_env_string+0x4d/0x4d
[486832.953431] Code: f9 ff 8b 43 74 c7 43 70 00 00 00 00 85 c0 74 0e ff
08 0f 94 c2 84 d2 74 05 e8 c7 6b e1 ff 8b 43 48 c7 43 74 00 00 00 00 83
e0 fe <8b> 50 10 89 d8 ff 52 34 83 f8 01 89 c7 0f 85 21 02 00 00 8b 53
[486832.953431] EIP: [<c12a4dd0>] xfrm_output_resume+0x61/0x29f SS:ESP
0068:c1407c44
[486832.953431] CR2: 0000000000000010
[486833.573872] ---[ end trace ed321ebdc197b3d7 ]---
[486833.578576] Kernel panic - not syncing: Fatal exception in interrupt
[486833.582572] Rebooting in 60 seconds..

(gdb) list *xfrm_output_resume+0x61
0xc12a4dd0 is in xfrm_output_resume (net/xfrm/xfrm_output.c:125).
120     int xfrm_output_resume(struct sk_buff *skb, int err)
121     {
122             while (likely((err = xfrm_output_one(skb, err)) == 0)) {
123                     nf_reset(skb);
124
125                     err = skb_dst(skb)->ops->local_out(skb);
126                     if (unlikely(err != 1))
127                             goto out;
128
129                     if (!skb_dst(skb)->xfrm)

Not knowing anything much about networking in the kernel I can't go any
further, but I'm happy to try out patches and poke around with a little
guidance.

I should add that the box doesn't reboot after 60 seconds and the
watchdog doesn't seem to kick in either, but that's clearly not a
networking issue. It reboots fine with the 'reboot' command.

Cheers,
Chris

-- 
Chris Boot
bootc@xxxxxxxxx
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