Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)

Linus Torvalds
2011-08-23T21:20:49Z

On Tue, Aug 23, 2011 at 2:08 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>
> Again, can we steal one of the padding fields to use for that state
> variable?  We have two 16-bit padding fields; one for cs and one for ss.

We can steal them for passing the information to the user, but no, I
don't think we can use them to then take the information *from* the
user.

Somebody may well be setting up a 'pt_regs' structure on his own, and
simply not fill in the padding, resulting in random data in those
fields.

Linus