Messages in this thread | | | Date | Sun, 29 Nov 2020 17:50:05 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC PATCH v0 00/19] x86/insn: Add an insn_decode() API |
| |
On Fri, 27 Nov 2020 09:45:39 -0800 Andy Lutomirski <luto@amacapital.net> wrote:
> On Tue, Nov 24, 2020 at 9:46 AM Borislav Petkov <bp@alien8.de> wrote: > > > > 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? > > Is -22 (-EINVAL) the same error it returns if you pass in garbage? > How hard would it be to teach it to return a different error code when > the buffer is too small? >
Good point. I think we can return, e.g. -EFAULT if we failed in get_next(). Then, we can read out next page, for example.
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
| |