Re: [RFC PATCH v0 00/19] x86/insn: Add an insn_decode() API
From: Borislav Petkov
Date: Tue Nov 24 2020 - 12:46:55 EST
On Tue, Nov 24, 2020 at 11:19:33AM +0100, Borislav Petkov wrote:
> In any case, at least the case where I give it
>
> 0x48 0xcf 0x48 0x83
>
> and say that buf size is 4, should return an error because the second
> insn is incomplete. So I need to go look at that now.
Ok, got it:
./arch/x86/tools/insn_sanity: Success: decoded and checked 10000 random instructions with 0 errors (seed:0x826fdf9c)
insn buffer:
0x48 0xcf 0x48 0x83 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90 0x90
supplied buf size: 15, ret 0
supplied buf size: 2, ret 0
supplied buf size: 3, ret 0
supplied buf size: 4, ret 0
supplied buf size: 1, ret -22
the current decoder simply decodes the *first* insn in the buffer it
encounters and that's it.
When you give it a buffer of size smaller than the first instruction:
supplied buf size: 1, ret -22
while the first insn is 2 bytes long:
0x48 0xcf (IRETQ)
then it signals an error.
Andy, does that work for your use cases?
--
Regards/Gruss,
Boris.
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