Using Polycom video conferencing software my homebrew linux NAT router  
crashes with attached kernel oops message.
This error can be reproduced also using kernel 3.2.54. Kernel 2.6.35  
seems to be stable.

Disabling nf_nat_h323 and nf_conntrack_h323 avoids crash - but video  
conferencing software is no more usable.


===================================================================================
  BUG: unable to handle kernel paging request at 00100104
IP: [<f8214f07>] nf_ct_unlink_expect_report+0x57/0xf0 [nf_conntrack]
*pdpt = 00000000359aa001 *pde = 0000000000000000
Oops: 0002 [#1] SMP
Modules linked in: nf_conntrack_netlink nfnetlink xt_mac xt_TCPMSS  
ipt_MASQUERADE
  xt_pkttype xt_multiport xt_REDIRECT xt_nat iptable_mangle xt_LOG  
xt_limit af_packet
  act_mirred cls_u32 sch_ingress sch_hfsc ifb xt_tcpudp ip6t_REJECT ipt_REJECT
  ip6table_raw iptable_raw xt_CT iptable_filter nf_nat_pptp nf_nat_proto_gre
  nf_conntrack_proto_udplite nf_conntrack_proto_dccp ip6table_mangle  
iptable_nat
  nf_nat_ipv4 nf_nat_sip nf_nat_irc nf_nat_snmp_basic nf_conntrack_snmp
  nf_conntrack_broadcast nf_nat_h323 nf_nat_tftp nf_nat_ftp nf_nat  
nf_conntrack_h323
  nf_conntrack_tftp nf_conntrack_proto_sctp nf_conntrack_sip nf_conntrack_irc
  nf_conntrack_pptp nf_conntrack_proto_gre nf_conntrack_ftp nf_conntrack_ipv4
  nf_defrag_ipv4 ip_tables xt_conntrack nf_conntrack ip6table_filter ip6_tables
  x_tables padlock_sha padlock_aes e_powersaver freq_table mperf via_cputemp
  hwmon_vid serio_raw pcspkr i2c_viapro ehci_pci fan thermal processor 8139too
  sg thermal_sys button shpchp 8139cp pci_hotplug mii via_agp ext4 crc16 jbd2
  pata_via sata_via libata sd_mod scsi_mod ohci_hcd uhci_hcd ehci_hcd
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.28-9500-smp_m #1
Hardware name:    /CN700-8237, BIOS 6.00 PG 08/30/2007
task: c07ce180 ti: f6408000 task.ti: c07c2000
EIP: 0060:[<f8214f07>] EFLAGS: 00210206 CPU: 0
EIP is at nf_ct_unlink_expect_report+0x57/0xf0 [nf_conntrack]
EAX: 00100100 EBX: eb636bc0 ECX: 00000000 EDX: eb461540
ESI: c0804e00 EDI: eb461544 EBP: f6409f08 ESP: f6409eec
  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
CR0: 8005003b CR2: 00100104 CR3: 359d4000 CR4: 000006b0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400
Stack:
  00000000 00200286 f6409f08 c0244bd8 eb636bc0 00100100 00000000 f6409f18
  f8215687 f598ede8 c0804e00 f6409f28 f8211c99 f598ede8 f598ee50 f6409f5c
  f8212e5e 00000003 00000000 00000000 00000004 eb461514 f598ede8 00000000
Call Trace:
  [<c0244bd8>] ? del_timer+0x48/0x70
  [<f8215687>] nf_ct_remove_expectations+0x47/0x60 [nf_conntrack]
  [<f8211c99>] nf_ct_delete_from_lists+0x59/0x90 [nf_conntrack]
  [<f8212e5e>] death_by_timeout+0x14e/0x1c0 [nf_conntrack]
  [<f8212d10>] ? nf_conntrack_set_hashsize+0x190/0x190 [nf_conntrack]
  [<c024442d>] call_timer_fn+0x1d/0x80
  [<c024461e>] run_timer_softirq+0x18e/0x1a0
  [<f8212d10>] ? nf_conntrack_set_hashsize+0x190/0x190 [nf_conntrack]
  [<c023e6f3>] __do_softirq+0xa3/0x170
  [<c023e650>] ? __local_bh_enable+0x70/0x70
  <IRQ>
  [<c023e587>] ? irq_exit+0x67/0xa0
  [<c0202af6>] ? do_IRQ+0x46/0xb0
  [<c027ad05>] ? clockevents_notify+0x35/0x110
  [<c066ac6c>] ? common_interrupt+0x2c/0x40
  [<c056e3c1>] ? cpuidle_enter_state+0x41/0xf0
  [<c056e6fb>] ? cpuidle_idle_call+0x8b/0x100
  [<c02085f8>] ? arch_cpu_idle+0x8/0x30
  [<c027314b>] ? cpu_idle_loop+0x4b/0x140
  [<c0273258>] ? cpu_startup_entry+0x18/0x20
  [<c066056d>] ? rest_init+0x5d/0x70
  [<c0813ac8>] ? start_kernel+0x2ec/0x2f2
  [<c081364f>] ? repair_env_string+0x5b/0x5b
  [<c0813269>] ? i386_start_kernel+0x33/0x35
Code: 8b 7b 0c 8b b6 98 00 00 00 85 c0 89 07 74 03 89 78 04 c7 43 0c 00
  02 20 00 83 ae ec 05 00 00 01 8b 03 8b 7b 04 85 c0 89 07 74 03 <89> 78
  04 8b 43 7c c7 03 00 01 10 00 c7 43 04 00 02 20 00 80 6c
EIP: [<f8214f07>] nf_ct_unlink_expect_report+0x57/0xf0 [nf_conntrack]  
SS:ESP 0068:f6409eec
CR2: 0000000000100104
---[ end trace 79fe2e6b81f54dee ]---
Kernel panic - not syncing: Fatal exception in interrupt
Rebooting in 300 seconds..
===================================================================================


Polycom Version: 3.1-44477
running on device: Apple iPad Mini
using operating system: iOS Version: 7.0.4


Attached also my kernel config. Hopefully someone could help...

BR, Toni