General Protection Fault in prelist_remove()

Hi,

I caught a General protection fault in prelist_remove. Any clues what 
this might be?

FreeBSD-10 from one month back approx.

> ffffffff80a95810 <prelist_remove>:
> ffffffff80a95810:       55                      push   %rbp
> ffffffff80a95811:       48 89 e5                mov    %rsp,%rbp
> ffffffff80a95814:       41 57                   push   %r15
> ffffffff80a95816:       41 56                   push   %r14
> ffffffff80a95818:       53                      push   %rbx
> ffffffff80a95819:       48 83 ec 38             sub    $0x38,%rsp
> ffffffff80a9581d:       49 89 ff                mov    %rdi,%r15
> ffffffff80a95820:       48 8b 04 25 c0 de 3b    mov    0xffffffff813bdec0,%rax
> ffffffff80a95827:       81
> ffffffff80a95828:       48 89 45 e0             mov    %rax,-0x20(%rbp)
> ffffffff80a9582c:       49 c7 47 44 00 00 00    movq   $0x0,0x44(%r15)
> ffffffff80a95833:       00
> ffffffff80a95834:       41 f6 47 6c 01          testb  $0x1,0x6c(%r15)
> ffffffff80a95839:       74 4d                   je     ffffffff80a95888 <prelist_remove+0x78>
> ffffffff80a9583b:       4c 89 ff                mov    %r15,%rdi
> ffffffff80a9583e:       e8 fd 00 00 00          callq  ffffffff80a95940 <nd6_prefix_offlink>
> ffffffff80a95843:       41 89 c6                mov    %eax,%r14d
> ffffffff80a95846:       45 85 f6                test   %r14d,%r14d
> ffffffff80a95849:       74 3d                   je     ffffffff80a95888 <prelist_remove+0x78>
> ffffffff80a9584b:       8b 04 25 c4 a6 56 81    mov    0xffffffff8156a6c4,%eax
> ffffffff80a95852:       85 c0                   test   %eax,%eax
> ffffffff80a95854:       74 32                   je     ffffffff80a95888 <prelist_remove+0x78>
> ffffffff80a95856:       49 8d 77 20             lea    0x20(%r15),%rsi
> ffffffff80a9585a:       48 8d 7d b0             lea    -0x50(%rbp),%rdi
> ffffffff80a9585e:       e8 1d fa fd ff          callq  ffffffff80a75280 <ip6_sprintf>
> ffffffff80a95863:       41 0f b6 4f 78          movzbl 0x78(%r15),%ecx
> ffffffff80a95868:       4d 8b 07                mov    (%r15),%r8
> ffffffff80a9586b:       49 83 c0 28             add    $0x28,%r8
> ffffffff80a9586f:       bf 03 00 00 00          mov    $0x3,%edi
> ffffffff80a95874:       48 c7 c6 c6 17 fa 80    mov    $0xffffffff80fa17c6,%rsi
> ffffffff80a9587b:       48 89 c2                mov    %rax,%rdx
> ffffffff80a9587e:       45 89 f1                mov    %r14d,%r9d
> ffffffff80a95881:       30 c0                   xor    %al,%al
> ffffffff80a95883:       e8 08 f0 e5 ff          callq  ffffffff808f4890 <log>
> ffffffff80a95888:       41 83 7f 7c 00          cmpl   $0x0,0x7c(%r15)
> ffffffff80a9588d:       7f 6c                   jg     ffffffff80a958fb <prelist_remove+0xeb>
> ffffffff80a9588f:       49 8b 47 08             mov    0x8(%r15),%rax
> ffffffff80a95893:       48 85 c0                test   %rax,%rax
> ffffffff80a95896:       74 0a                   je     ffffffff80a958a2 <prelist_remove+0x92>
> ffffffff80a95898:       49 8d 4f 08             lea    0x8(%r15),%rcx
> ffffffff80a9589c:       48 39 48 10             cmp    %rcx,0x10(%rax)
^^^^ crash here
> ffffffff80a958a0:       75 72                   jne    ffffffff80a95914 <prelist_remove+0x104>
> ffffffff80a958a2:       49 8b 4f 10             mov    0x10(%r15),%rcx

Non-reproducable.

--HPS