Kernel panic at strstr() function called by an unsigned module.

Issue

Kernel panic occurred during NULL pointer dereference inside strstr() function.

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [] strstr+0x26/0xa0
PGD c4cc6a067 PUD c8b006067 PMD 0 
Oops: 0000 [#1] SMP 
last sysfs file: /sys/devices/system/cpu/online
CPU 19 
Modules linked in: fbk_20160515111209(U) nfs lockd fscache auth_rpcgss nfs_acl sunrpc mptctl mptbase autofs4 coretemp cpufreq_ondemand acpi_cpufreq freq_table mperf ipv6 iTCO_wdt iTCO_vendor_support ipmi_devintf microcode power_meter acpi_ipmi ipmi_si ipmi_msghandler sg sb_edac edac_core lpc_ich mfd_core bnx2x libcrc32c mdio igb dca i2c_algo_bit i2c_core ptp pps_core ext4 jbd2 mbcache dm_round_robin sd_mod crc_t10dif megaraid_sas wmi dm_multipath dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]

Pid: 23537, comm: svn Not tainted 2.6.32-504.12.2.el6.x86_64 #1 Cisco Systems Inc UCSC-C220-M3L/UCSC-C220-M3L
RIP: 0010:[]  [] strstr+0x26/0xa0
RSP: 0018:ffff880bff94de38  EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffffa03fe234
RDX: ffffffffa03fe213 RSI: ffffffffa03fe20e RDI: 0000000000000000
RBP: ffff880bff94de38 R08: 0000000000000073 R09: 0000000000000000
R10: 0000000000000005 R11: 000000000000000b R12: ffff88007d458fc4
R13: 0000000000000008 R14: 0000000000000000 R15: 00000000000026cd
FS:  00007fcf5f8d7740(0000) GS:ffff880028360000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000001072ac9000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process svn (pid: 23537, threadinfo ffff880bff94c000, task ffff88007b575500)
Stack:
 ffff880bff94de58 ffffffffa03f4ced 0000000000000001 00000000000552b4
 ffff880bff94ded8 ffffffffa03f4f78 ffff880bff94ded8 ffffffffa03f8e70
 ffff880b00000001 ffff88007d458000 ffff88007d5ad000 ffff88007b648000
Call Trace:
 [] fb_ignore_file+0x1d/0xb0 [fbk_20160515111209]
 [] vhook_file_access_rename_hardlink+0x68/0x1a0 [fbk_20160515111209]
 [] ? fb_readlink_user_create+0x140/0x150 [fbk_20160515111209]
 [] __handle_access_rename_hardlink+0x11e/0x130 [fbk_20160515111209]
 [] fb_sys_rename_native+0x8d/0x200 [fbk_20160515111209]
 [] system_call_fastpath+0x16/0x1b
Code: 00 00 00 00 00 80 3e 00 55 48 89 f8 48 89 e5 74 15 48 89 f2 90 48 83 c2 01 80 3a 00 75 f7 41 89 d2 41 29 f2 75 02 c9 c3 45 31 c9 <80> 38 00 48 89 c1 74 11 66 90 48 83 c1 01 80 39 00 75 f7 41 89 
RIP  [] strstr+0x26/0xa0