Re: [PATCH v9 1/1] ptrace,syscall_user_dispatch: checkpoint/restore support for SUD

[Oleg Nesterov]

On 02/13, Gregory Price wrote:
>
> On Mon, Feb 13, 2023 at 09:26:21PM +0100, Thomas Gleixner wrote:
> > On Fri, Feb 10 2023 at 02:25, Gregory Price wrote:
> > > +struct ptrace_sud_config {
> > > +	__u64 mode;
> > > +	__s8 *selector;
> >
> > How is this correct for a 32bit ptracer running on a 64bit kernel? Aside
> > of not wiring up the compat syscall without any argumentation in the
> > changelog.
> >
>
> I'm having a little trouble wrapping my head around what is "right" here
> with regard to compat.  Granted I've never had to deal with compat
> issues, so please excuse the ignorance if this is a trivial issue.

The problem is the sizeof(selector). 4 bytes for 32bit ptracer but the
kernel will write 8 bytes. I think you should make "selector" __u64 too.

Oleg.