Server crashed with panic message "BUG: unable to handle kernel NULL pointer dereference at (null)"

Issue

• Server crash has occurred generating a vmcore where following logs were observed in the kernel ring buffer :

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffffa03f7584>] lru_touch+0x104/0x330 [dsa_filter]
PGD 0 
Oops: 0002 [#1] SMP 
last sysfs file: /sys/devices/pci0000:00/0000:00:1c.2/0000:06:00.1/net/em4/speed
CPU 2 
Modules linked in: gsch(U) redirfs(U) dsa_filter(P)(U) nf_conntrack_ipv4 nf_defrag_ipv4 fuse iptable_filter ip_tables bridge stp llc autofs4 ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables ipv6 uinput microcode iTCO_wdt iTCO_vendor_support dcdbas power_meter sb_edac edac_core ses enclosure lpc_ich mfd_core shpchp tg3 ptp pps_core sg ext4 jbd2 mbcache usb_storage sd_mod crc_t10dif ahci wmi qla2xxx scsi_transport_fc scsi_tgt megaraid_sas dm_mirror dm_region_hash dm_log dm_mod [last unloaded: dsa_filter]

Pid: 3123, comm: named Tainted: P           ---------------    2.6.32-431.el6.x86_64 #1 Dell Inc. PowerEdge M520/050YHY
RIP: 0010:[<ffffffffa03f7584>]  [<ffffffffa03f7584>] lru_touch+0x104/0x330 [dsa_filter]
RSP: 0018:ffff88061d9bb4d8  EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff880371899b08 RCX: 20c49ba5e353f7cf
RDX: 0000000000000000 RSI: ffff880371899b08 RDI: ffffffffa0475d60
RBP: ffff88061d9bb4f8 R08: ffff88061d9bb5f8 R09: 0000000000000000
R10: 00000000a1146ac0 R11: 0000000000000047 R12: ffffffffa0475c80
R13: ffffffffa0475d50 R14: 0000000000000001 R15: ffff88061d9bb501
FS:  00007f134e3f0700(0000) GS:ffff880045a40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000822521000 CR4: 00000000000407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process named (pid: 3123, threadinfo ffff88061d9ba000, task ffff880652dac080)
Stack:
 ffffffffa0475c80 ffff88061d9bb5e8 ffffffffa0475c80 0000000000000007
<d> ffff88061d9bb528 ffffffffa03f7af2 ffff88061d9bb5e8 0000000000000000
<d> ffff88036b800018 0000000000000001 ffff88061d9bb598 ffffffffa04038f0
Call Trace:
 [<ffffffffa03f7af2>] conntrack_lookup+0x342/0x5e0 [dsa_filter]
 [<ffffffffa04038f0>] core_pkt_filter+0x8d0/0xbd0 [dsa_filter]
 [<ffffffffa04040fd>] core_pkt_hook+0x50d/0x8b0 [dsa_filter]
 [<ffffffffa0457afd>] lin_nf_packet_wrapper.clone.0+0x21d/0x3d0 [dsa_filter]
 [<ffffffffa0458870>] ? lin_pkt_get_frame_header+0x0/0x5d0 [dsa_filter]
 [<ffffffffa04584d0>] ? lin_pkt_get_length+0x0/0x20 [dsa_filter]
 [<ffffffffa0458730>] ? lin_pkt_read_start+0x0/0x140 [dsa_filter]
 [<ffffffffa0458590>] ? lin_pkt_read+0x0/0x1a0 [dsa_filter]
 [<ffffffffa0458540>] ? lin_pkt_read_end+0x0/0x50 [dsa_filter]
 [<ffffffffa04584f0>] ? lin_pkt_get_valid_checksum+0x0/0x50 [dsa_filter]
 [<ffffffff81499f90>] ? ip_finish_output+0x0/0x310
 [<ffffffffa0457e5c>] lin_nf_packet_wrapper_all.clone.1+0x1ac/0x1e0 [dsa_filter]
 [<ffffffff81499f90>] ? ip_finish_output+0x0/0x310
 [<ffffffffa0457eb1>] lin_nf_packet_wrapper_inet+0x21/0x30 [dsa_filter]
 [<ffffffff814893a9>] nf_iterate+0x69/0xb0
 [<ffffffff81499f90>] ? ip_finish_output+0x0/0x310
 [<ffffffff81489566>] nf_hook_slow+0x76/0x120
 [<ffffffff81499f90>] ? ip_finish_output+0x0/0x310
 [<ffffffff8149a344>] ip_output+0xa4/0xc0
 [<ffffffff8149961f>] ? __ip_local_out+0x9f/0xb0
 [<ffffffff81499655>] ip_local_out+0x25/0x30
 [<ffffffff8149967b>] ip_send_skb+0x1b/0x80
 [<ffffffff814bc9b9>] udp_send_skb+0x119/0x3d0
 [<ffffffff81498720>] ? ip_generic_getfrag+0x0/0xb0
 [<ffffffff814bd04b>] udp_sendmsg+0x2eb/0x930
 [<ffffffff814c5b8a>] inet_sendmsg+0x4a/0xb0
 [<ffffffff81447e03>] sock_sendmsg+0x123/0x150
 [<ffffffff8109b2a0>] ? autoremove_wake_function+0x0/0x40
 [<ffffffff8105572c>] ? check_preempt_curr+0x7c/0x90
 [<ffffffff81065c5e>] ? try_to_wake_up+0x24e/0x3e0
 [<ffffffff81447c54>] ? move_addr_to_kernel+0x64/0x70
 [<ffffffff814495f6>] __sys_sendmsg+0x406/0x420
 [<ffffffff810b1130>] ? do_futex+0x100/0xb60
 [<ffffffff81449819>] sys_sendmsg+0x49/0x90
 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
Code: a4 00 00 00 0f 1f 00 4d 85 e4 0f 84 07 01 00 00 4d 8d ac 24 d0 00 00 00 4c 89 ef e8 67 2d 06 00 48 8b 53 18 48 8b 43 10 4d 85 e4 <48> 89 02 48 89 50 08 48 8d 43 10 48 c7 43 10 00 00 00 00 48 c7 
RIP  [<ffffffffa03f7584>] lru_touch+0x104/0x330 [dsa_filter]
 RSP <ffff88061d9bb4d8>
CR2: 0000000000000000