GELI BIOS weirdness

Eric McCorkle eric at metricspace.net
Mon Feb 13 20:58:54 UTC 2017


On 02/13/2017 15:36, Dimitry Andric wrote:

> This disassembles to:
> 
>    0:   66 0f 38 f6 f0          adcx   %eax,%esi
>    5:   31 c6                   xor    %eax,%esi
>    7:   8b 4d 14                mov    0x14(%ebp),%ecx
>    a:   89 cf                   mov    %ecx,%edi
>    c:   c1 ff 1f                sar    $0x1f,%edi
>    f:   8b                      .byte 0x8b

Note that this was truncated, so the sar and .byte are probably a
truncated instruction.

Also, when I had printfs in place, I could see the call instructions.

> My first guess would be that the code simply jumped into garbage.  But
> can you post the complete .o file somewhere for inspection?

Attached.
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