Re: + fully-honor-vdso_enabled.patch added to -mm tree

[Oleg Nesterov <oleg@tv-sign.ru>]

On 03/02, Chuck Ebbert wrote:
>
> John Reiser wrote:
> > The value of ->sysenter_return is interpreted in user space by the
> > sysexit instruction; nobody else cares what the value is.  The kernel
> > is not required to provide a good value when vdso_enabled is zero,
> > because the kernel has not told the process that sysenter is valid
> > (by setting AT_SYSINFO.)
> 
> Doesn't matter because a malicious user can still execute sysenter.
> We do have to deal with that somehow, so we have to put something
> safe in there.

Yes, but a malicious user can't make any harm to the system, sysexit
jumps to ->sysenter_return when user_mode() is true, right?

(I am asking because I don't know in details what sysexit does).

Oleg.