NULL pointer dereference in function EfsOpenHelper() of the unsigned kernel module efs100 .

Issue

• Kernel panic due to 'EfsOpenHelper()' function of unsigned kernel module 'efs100'.

crash> log
[../Snip\..]
[1522481.765090] BUG: unable to handle kernel NULL pointer dereference at 0000000000000064
[1522481.774668] IP: [<ffffffffc0611346>] EfsOpenHelper+0x96/0x220 [efs100]
[1522481.782525] PGD 8000000d8da22067 PUD d8da21067 PMD 0 
[1522481.788881] Oops: 0000 [#1] SMP 
[1522481.793114] Modules linked in: iptable_filter sctp_diag sctp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag nfsv3 nfs_acl rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache lofs(OE) efs100(POE) rpcrdma sunrpc ib_isert iscsi_target_mod ib_iser libiscsi scsi_transport_iscsi ib_srpt target_core_mod ib_srp scsi_transport_srp scsi_tgt ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm sb_edac edac_core intel_powerclamp coretemp dm_round_robin intel_rapl iosf_mbi kvm_intel kvm irqbypass crc32_pclmul ghash_clmulni_intel iTCO_wdt aesni_intel iTCO_vendor_support lrw gf128mul glue_helper ablk_helper ib_core joydev cryptd pcspkr ipmi_si ipmi_devintf sg ipmi_msghandler wmi lpc_ich shpchp acpi_power_meter dm_multipath binfmt_misc ip_tables xfs libcrc32c sd_mod
[1522481.880412]  crc_t10dif crct10dif_generic i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm crct10dif_pclmul crct10dif_common drm crc32c_intel megaraid_sas enic i2c_core dm_mirror dm_region_hash dm_log dm_mod
[1522481.904655] CPU: 18 PID: 8496 Comm: acme Tainted: P           OE  ------------   3.10.0-693.11.6.el7.x86_64 #1
[1522481.916512] Hardware name: Cisco Systems Inc UCSB-B200-M3/UCSB-B200-M3, BIOS B200M3.2.2.6d.0.062220160055 06/22/2016
[1522481.928953] task: ffff88202dabeeb0 ti: ffff882024b74000 task.ti: ffff882024b74000
[1522481.937990] RIP: 0010:[<ffffffffc0611346>]  [<ffffffffc0611346>] EfsOpenHelper+0x96/0x220 [efs100]
[1522481.948763] RSP: 0018:ffff882024b77c08  EFLAGS: 00010282
[1522481.955170] RAX: 0000000000000000 RBX: ffff881000f26000 RCX: 00000000ffffffff
[1522481.963815] RDX: ffffffffc06207ce RSI: ffff880fbcfc0c00 RDI: ffff881000f26000
[1522481.972451] RBP: ffff882024b77c38 R08: 000000000000801d R09: ffff880d00fc250c
[1522481.981094] R10: 00000000000003e0 R11: 0000000000000000 R12: ffff880fbcfc0c00
[1522481.989741] R13: 000000000000801d R14: ffff88202dabeeb0 R15: 0000000000000000
[1522481.998389] FS:  00007f86c33a3740(0000) GS:ffff88103fc80000(0000) knlGS:0000000000000000
[1522482.008107] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1522482.015003] CR2: 0000000000000064 CR3: 00000007e3616000 CR4: 00000000001607e0
[1522482.023648] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[1522482.032296] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[1522482.040944] Call Trace:
[1522482.044149]  [<ffffffffc06119aa>] EfsOpen+0x7a/0x90 [efs100]
[1522482.050950]  [<ffffffff81200427>] do_dentry_open+0x1a7/0x2e0
[1522482.057744]  [<ffffffff812b409c>] ? security_inode_permission+0x1c/0x30
[1522482.065611]  [<ffffffffc0611930>] ? CleanupUnode+0x40/0x40 [efs100]
[1522482.073091]  [<ffffffff812005fa>] vfs_open+0x5a/0xb0
[1522482.079109]  [<ffffffff8120e2e8>] ? may_open+0x68/0x110
[1522482.085419]  [<ffffffff8121175d>] do_last+0x1ed/0x12c0
[1522482.091634]  [<ffffffff812128f2>] path_openat+0xc2/0x490
[1522482.098044]  [<ffffffff812b96fa>] ? inode_has_perm.isra.33.constprop.64+0x2a/0x30
[1522482.107082]  [<ffffffff81214e8b>] do_filp_open+0x4b/0xb0
[1522482.113491]  [<ffffffff8122213a>] ? __alloc_fd+0x8a/0x130
[1522482.119996]  [<ffffffff812019c3>] do_sys_open+0xf3/0x1f0
[1522482.126401]  [<ffffffff81201ade>] SyS_open+0x1e/0x20
[1522482.132419]  [<ffffffff816b89fd>] system_call_fastpath+0x16/0x1b
[1522482.139601] Code: 00 00 00 01 31 c0 45 89 e8 4c 89 e1 48 c7 c2 ce 07 62 c0 be 10 00 00 00 48 89 df e8 35 cd 00 00 4c 89 e6 48 89 df e8 4a 7b 00 00 <f6> 40 64 04 49 89 c6 74 31 41 f6 c5 02 74 2b 8b 83 c8 00 00 00 
[1522482.166731] RIP  [<ffffffffc0611346>] EfsOpenHelper+0x96/0x220 [efs100]
[1522482.174681]  RSP <ffff882024b77c08>
[1522482.179044] CR2: 0000000000000064