Re: Another x86_64 disassembler crash

["Jan Beulich" <JBeulich at novell dot com>]

>Something is still strange in my testcase; the 32-bit and 64-bit
>disassemblers produce different output, but the differences are of
the
>forms:
>
>-ffffffff8055fb2e:      2e                      cs
>-ffffffff8055fb2f:      2e                      cs
>-ffffffff8055fb30:      2e                      cs
>-ffffffff8055fb31:      2e 2e 2e 2e 2e 2e 2e    or
%cs:0xffffffffffffffee(%rcx),%ch
>-ffffffff8055fb38:      2e 2e 2e 2e 2e 2e 2e 
>-ffffffff8055fb3f:      2e 2e 2e 2e 2e 2e 0a 
>-ffffffff8055fb46:      00 00 
>-ffffffff8055fb48:      3c 37                   cmp    $0x37,%al
>+ffffffff8055fb2e:      2e 2e 2e 2e 2e 2e 2e    or     %cs:(%rax),%al
>+ffffffff8055fb35:      2e 2e 2e 2e 2e 2e 2e 
>+ffffffff8055fb3c:      2e 2e 2e 2e 2e 2e 2e 
>+ffffffff8055fb43:      2e 2e 0a 00 
>+ffffffff8055fb47:      00 3c 37                add %bh,(%rdi,%rsi,1)

This difference is caused by a buffer overflow, which triggers (due to
alignment differences) later on 64-bits than on 32. Preparing a
patch...

>and
>
>-ffffffff805be630:      43 17                   rexYZ popq   %dl
>+ffffffff805be630:      43 17                   rexYZ popq   %bp,%si

This one I can't explain at all. Opcode 0x17 is invalid in 64-bit mode,
and clearly marked as such in the tables. Whatever binutils version I
use, I get "rexYZ (bad)" as expected.

Bottom line is, more context might be needed to understand why things
are going wrong...

Jan