NULL pointer dereference in function xdr_string [mvfs]

Issue

Kernel panic with error "BUG: unable to handle kernel NULL pointer dereference at (null)"
Bug at IP [] xdr_string+0x31/0x9e [mvfs]" (in function xdr_string of mvfs kernel module)

Call trace:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffffa06649d7>] xdr_string+0x31/0x9e [mvfs]
PGD 1a01ef067 PUD 860af8067 PMD 0 
Oops: 0000 [#1] SMP 
last sysfs file: /sys/devices/system/cpu/online
CPU 5 
Modules linked in: ib_ipoib ib_cm mlx4_en mlx4_ib ib_sa ib_mad ib_core mlx4_core mpt2sas scsi_transport_sas raid_class mptctl mptbase ipmi_devintf mvfs(U) iptable_filter ip_tables autofs4 nfs lockd fscache auth_rpcgss nfs_acl sunrpc bnx2fc cnic uio fcoe libfcoe libfc cpufreq_ondemand acpi_cpufreq freq_table mperf bonding 8021q garp stp llc ipv6 emcpvlumd(P)(U) emcpxcrypt(P)(U) emcpdm(P)(U) emcpgpx(P)(U) emcpmpx(P)(U) emcp(P)(U) cdc_ether usbnet mii microcode i2c_i801 i2c_core iTCO_wdt iTCO_vendor_support shpchp ioatdma sg igb dca ptp pps_core ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif ahci wmi megaraid_sas qla2xxx scsi_transport_fc scsi_tgt dm_mirror dm_region_hash dm_log dm_mod [last unloaded: mvfs]

Pid: 2324, comm: python3 Tainted: P           ---------------    2.6.32-358.6.2.el6.x86_64 #1 IBM System x3650 M4 : -[7915E3G]-/00Y8362
RIP: 0010:[<ffffffffa06649d7>]  [<ffffffffa06649d7>] xdr_string+0x31/0x9e [mvfs]
RSP: 0018:ffff88010740f4d8  EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff88010740f548 RCX: ffffffffffffffff
RDX: 00000000000003ff RSI: ffff8801c1f4c6c8 RDI: 0000000000000000
RBP: ffff88010740f508 R08: ffff8801c1f4c690 R09: ffff880101e00047
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 00000000000003ff R14: ffffffffa0663761 R15: ffff8812bcbdb080
FS:  00007ffe764f1700(0000) GS:ffff8800282a0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000012267b000 CR4: 00000000000407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process python3 (pid: 2324, threadinfo ffff88010740e000, task ffff8801082b2ae0)
Stack:
 ffff88186b0b4080 ffff8801082b2ae0 ffff88010740f518 ffff88010740f548
<d> ffff8801c1f4c690 ffff880c5a8c3200 ffff88010740f518 ffffffffa066307b
<d> ffff88010740f538 ffffffffa066332e ffff880c5a8c3200 ffff880101e00070
Call Trace:
 [<ffffffffa066307b>] xdr_ks_canon_pname_p_t+0x13/0x15 [mvfs]
 [<ffffffffa066332e>] xdr_albd_find_server_req_t+0x4a/0x5b [mvfs]
 [<ffffffffa066379c>] mvfs_linux_xdr_encode_albd_find_server+0x3b/0x59 [mvfs]
 [<ffffffffa0533bd8>] ? xdr_encode_opaque+0x18/0x20 [sunrpc]
 [<ffffffffa0529e44>] rpcauth_wrap_req+0x84/0xb0 [sunrpc]
 [<ffffffffa051e150>] ? call_transmit+0x0/0x2c0 [sunrpc]
 [<ffffffffa051e2f5>] call_transmit+0x1a5/0x2c0 [sunrpc]
 [<ffffffffa0528997>] __rpc_execute+0x77/0x350 [sunrpc]
 [<ffffffff811c2dc2>] ? fsnotify_clear_marks_by_inode+0x32/0xf0
 [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0
 [<ffffffffa0528cd1>] rpc_execute+0x61/0xa0 [sunrpc]
 [<ffffffffa051f3a5>] rpc_run_task+0x75/0x90 [sunrpc]
 [<ffffffffa051f4c2>] rpc_call_sync+0x42/0x70 [sunrpc]
 [<ffffffffa066d0e9>] mdki_linux_clnt_call+0x70/0x123 [mvfs]
 [<ffffffffa0656b47>] mfscall_int+0x3cd/0x10ac [mvfs]
 [<ffffffffa0665938>] ? mvfs_linux_vfsp_to_fsid+0x2a/0x30 [mvfs]
 [<ffffffffa0658534>] mfscall+0x98/0xbb [mvfs]
 [<ffffffffa066320e>] ? xdr_albd_find_server_reply_t+0x0/0x7c [mvfs]
 [<ffffffffa06632e4>] ? xdr_albd_find_server_req_t+0x0/0x5b [mvfs]
 [<ffffffffa0658799>] mvfs_bindsvr_port+0x242/0x419 [mvfs]
 [<ffffffffa066320e>] ? xdr_albd_find_server_reply_t+0x0/0x7c [mvfs]
 [<ffffffffa0658a3a>] mfs_vwcall+0xca/0x72e [mvfs]
 [<ffffffffa062ee83>] ? mfs_getattr+0xb12/0xc17 [mvfs]
 [<ffffffffa0662993>] ? xdr_view_lookup_reply_t+0x0/0x9c [mvfs]
 [<ffffffffa0662a2f>] ? xdr_view_lookup_req_t+0x0/0x71 [mvfs]
 [<ffffffffa0654791>] mfs_clnt_lookup+0x395/0xeb6 [mvfs]
 [<ffffffffa062fa75>] mvfs_lookup_ctx+0x84a/0xba8 [mvfs]
 [<ffffffffa062cc0a>] ? mfs_ac_timedout+0x2a5/0x903 [mvfs]
 [<ffffffffa06297fc>] ? mvfs_devadjust+0x72/0x7e [mvfs]
 [<ffffffffa0665751>] mvfs_linux_lookup_wrapper+0x108/0x119 [mvfs]
 [<ffffffffa0664616>] ? mvfs_get_thread_ptr+0x19/0x1b [mvfs]
 [<ffffffffa0669c2a>] vnode_iop_lookup+0x82/0x460 [mvfs]
 [<ffffffff811904e5>] do_lookup+0x1a5/0x230
 [<ffffffff8119077d>] __link_path_walk+0x20d/0x1030
 [<ffffffff8104baa7>] ? pte_alloc_one+0x37/0x50
 [<ffffffff810aa3ee>] ? futex_wake+0x10e/0x120
 [<ffffffff8119182a>] path_walk+0x6a/0xe0
 [<ffffffff811919fb>] do_path_lookup+0x5b/0xa0
 [<ffffffff81192687>] user_path_at+0x57/0xa0
 [<ffffffff8121bdf6>] ? security_prepare_creds+0x16/0x20
 [<ffffffff8117ee10>] sys_faccessat+0xd0/0x1d0
 [<ffffffff8117ef28>] sys_access+0x18/0x20
 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
Code: 41 54 53 48 83 ec 18 0f 1f 44 00 00 8b 07 4c 8b 26 48 89 fb 41 89 d5 85 c0 74 07 83 f8 02 75 36 eb 16 31 c0 48 83 c9 ff 4c 89 e7 <f2> ae 48 f7 d1 48 ff c9 89 4d dc eb 1e 31 c0 48 c7 c2 08 33 67 
RIP  [<ffffffffa06649d7>] xdr_string+0x31/0x9e [mvfs]
 RSP <ffff88010740f4d8>
CR2: 0000000000000000