ip6_tables crash in socket_mt6_v1() due ipv6_find_hdr() returning bad offset

Issue

• ip6_tables crash in socket_mt6_v1() due ipv6_find_hdr() returning bad offset
• Kernel panic ending in exception RIP: socket_mt6_v1 and backtrace similar to:

RIP: 0010:[<ffffffffa033f762>]  [<ffffffffa033f762>] socket_mt6_v1+0xe2/0x524 [xt_socket]
 [<ffffffffa0396034>] ? ipv6_find_hdr+0x1a4/0x1d0 [ip6_tables]
 [<ffffffffa039647a>] ip6t_do_table+0x29a/0x6ec [ip6_tables]
 [<ffffffffa0369e74>] ? ipv6_frag_rcv+0xa24/0xe50 [ipv6]
 [<ffffffffa03f80c3>] ip6t_in_hook+0x23/0x30 [ip6table_mangle]
 [<ffffffff81474de9>] nf_iterate+0x69/0xb0
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffff81474fa4>] nf_hook_slow+0x74/0x110
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffffa03243c3>] nf_ct_frag6_output+0x73/0xe0 [nf_defrag_ipv6]
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffffa0324099>] ipv6_defrag+0x89/0xb0 [nf_defrag_ipv6]
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffff81474de9>] nf_iterate+0x69/0xb0
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffff81474fa4>] nf_hook_slow+0x74/0x110
 [<ffffffffa03491b0>] ? ip6_rcv_finish+0x0/0x50 [ipv6]
 [<ffffffffa0349572>] ipv6_rcv+0x372/0x460 [ipv6]
 [<ffffffff8144891b>] __netif_receive_skb+0x4ab/0x750
 [<ffffffff81166ae9>] ? ksize+0x19/0x80
 [<ffffffff8144acf8>] netif_receive_skb+0x58/0x60

or

    [exception RIP: socket_mt6_v1+226]
 #9 [ffff8800282a3768] ip6t_do_table at ffffffffa028f47a [ip6_tables]
#10 [ffff8800282a38f8] ip6t_in_hook at ffffffffa02fb0c3 [ip6table_mangle]
#11 [ffff8800282a3908] nf_iterate at ffffffff81474de9
#12 [ffff8800282a3958] nf_hook_slow at ffffffff81474fa4
#13 [ffff8800282a39d8] nf_ct_frag6_output at ffffffffa02083c3 [nf_defrag_ipv6]
#14 [ffff8800282a3a48] ipv6_defrag at ffffffffa0208099 [nf_defrag_ipv6]
#15 [ffff8800282a3a88] nf_iterate at ffffffff81474de9
#16 [ffff8800282a3ad8] nf_hook_slow at ffffffff81474fa4
#17 [ffff8800282a3b58] ipv6_rcv at ffffffffa0242572 [ipv6]
#18 [ffff8800282a3ba8] __netif_receive_skb at ffffffff8144891b
#19 [ffff8800282a3c08] netif_receive_skb at ffffffff8144acf8