Re: [Regression v4.2 ?] 32-bit seccomp-BPF returned errno values wrong in VM?

From: Denys Vlasenko
Date: Fri Aug 14 2015 - 07:58:15 EST

On 08/14/2015 12:59 AM, Andy Lutomirski wrote:
> On Thu, Aug 13, 2015 at 3:56 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>> On Thu, Aug 13, 2015 at 3:54 PM, Linus Torvalds
>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>> On Thu, Aug 13, 2015 at 3:49 PM, Linus Torvalds
>>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>>> Does the attached patch make sense and work?
>>> Btw, I'm not all that happy with it anyway.
>>> I still think Denys' patch also potentially changed what audit and
>>> strace see for %rax in the pt_regs to -ENOSYS, which I'm not convinced
>>> is a good change.
>>> But maybe that three-liner patch fixes the immediate problem that
>>> David sees. David?
>> Your patch fixes it for me. The seccomp compat selftests pass again
>> with audit enabled.
> Kees, would it be straightforward to rig up the seccomp tests to
> automatically test compat? The x86 selftests automatically test both
> native and compat, and that might be usable as a model. I did that
> because it's extremely easy to regress one and not the other.

BTW, why 64-bt code doesn't need this RAX read-back?

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