Kernel panic with NULL pointer dereference in ovs_vport_locate()

Issue

• System crashes with following messages in the kernel ring buffer :

[1205332.545595] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[1205332.554543] IP: [<ffffffffa04ebc8b>] ovs_vport_locate+0x3b/0x80 [openvswitch]
[1205332.562707] PGD 0 
[1205332.565151] Oops: 0000 [#1] SMP 
[1205332.568959] Modules linked in: fuse btrfs zlib_deflate raid6_pq xor vfat msdos fat binfmt_misc sfc_aoe(OF) onload(OF) sfc_char(OF) sfc_resource(OF) sfc_affinity(OF) sfc(OF) mtd veth ext4 mbcache jbd2 xt_addrtype xt_conntrack bridge stp llc [..]
[1205332.680295] CPU: 0 PID: 1309 Comm: ovs-vswitchd Tainted: GF       W  O--------------   3.10.0-229.el7.x86_64 #1
[1205332.691743] Hardware name: Dell Inc. PowerEdge R620/0KCKR5, BIOS 1.6.0 03/07/2013
[1205332.700284] task: ffff880fe4f34fa0 ti: ffff880fe177c000 task: ffff880fe177c000
[1205332.708825] RIP: 0010:[<ffffffffa04ebc8b>]  [<ffffffffa04ebc8b>] ovs_vport_locate+0x3b/0x80 [openvswitch]
[1205332.719702] RSP: 0018:ffff880fe177f970  EFLAGS: 00010286
[..]
[1205332.806851] Stack:
[1205332.809283]  ffff880fce553420 ffff880fce553414 ffff880fce553414 ffff880fe177f9b0
[1205332.817761]  ffffffffa04e4ee3 ffff880fe177fa40 ffff880fe6a52400 ffff880fce553414
[1205332.826238]  ffff880fe177f9f0 ffffffffa04e51b5 ffff880fdde0b240 ffffffffa04ee1b0
[1205332.834716] Call Trace:
[1205332.837637]  [<ffffffffa04e4ee3>] lookup_vport+0x23/0x150 [openvswitch]
[1205332.845209]  [<ffffffffa04e51b5>] ovs_vport_cmd_get+0x55/0xd0 [openvswitch]
[1205332.853171]  [<ffffffff8152c47d>] genl_family_rcv_msg+0x1cd/0x400
[1205332.860160]  [<ffffffff8152c6b0>] ? genl_family_rcv_msg+0x400/0x400
[1205332.867344]  [<ffffffff8152c741>] genl_rcv_msg+0x91/0xd0
[1205332.873460]  [<ffffffff8152a6a9>] netlink_rcv_skb+0xa9/0xc0
[1205332.879869]  [<ffffffff8152abd8>] genl_rcv+0x28/0x40
[1205332.885597]  [<ffffffff81529cbd>] netlink_unicast+0xed/0x1b0
[1205332.892100]  [<ffffffff8152a0b0>] netlink_sendmsg+0x330/0x770
[1205332.898703]  [<ffffffff8126bb95>] ? sock_has_perm+0x75/0x90
[1205332.905113]  [<ffffffff814e3240>] sock_sendmsg+0xb0/0xf0
[1205332.911235]  [<ffffffff812ed54d>] ? list_del+0xd/0x30
[1205332.917063]  [<ffffffff810a2354>] ? __wake_up+0x44/0x50
[1205332.923084]  [<ffffffff814e3679>] ___sys_sendmsg+0x3a9/0x3c0
[1205332.929590]  [<ffffffff814f8b39>] ? dev_get_by_name_rcu+0x29/0x90
[1205332.936580]  [<ffffffff81511032>] ? dev_ioctl+0x1f2/0x590
[1205332.942794]  [<ffffffff811aadf5>] ? kmem_cache_free+0x1b5/0x1e0
[1205332.949591]  [<ffffffff814e0395>] ? sock_do_ioctl+0x45/0x50
[1205332.955999]  [<ffffffff814e0aa0>] ? sock_ioctl+0x1f0/0x2c0
[1205332.962312]  [<ffffffff811d9a75>] ? do_vfs_ioctl+0x2e5/0x4c0
[1205332.968818]  [<ffffffff8126ef4e>] ? file_has_perm+0xae/0xc0
[1205332.975227]  [<ffffffff814e4561>] __sys_sendmsg+0x51/0x90
[1205332.981441]  [<ffffffff814e45b2>] SyS_sendmsg+0x12/0x20
[1205332.987463]  [<ffffffff81613da9>] system_call_fastpath+0x16/0x1b
[1205332.994353] Code: 49 89 f4 53 e8 f7 fd ff ff 48 8b 00 48 85 c0 48 8d 58 d8 75 0f eb 39 66 0f 1f 84 00 00 00 00 00 48 83 eb 28 48 8b 43 48 48 89 df <ff> 50 28 4c 89 e7 48 89 c6 e8 17 0c df e0 85 c0 75 0a 48 8b 43 
[1205333.016110] RIP  [<ffffffffa04ebc8b>] ovs_vport_locate+0x3b/0x80 [openvswitch]
[1205333.024368]  RSP <ffff880fe177f970>
[1205333.028448] CR2: 0000000000000028