Re: [PATCH 1/1] mm/madvise: replace ptrace attach requirement for process_madvise

[David Rientjes]

On Fri, 8 Jan 2021, Suren Baghdasaryan wrote:

> > > @@ -1197,12 +1197,22 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, 
> > > const struct iovec __user *, vec,
> > >               goto release_task;
> > >       }
> > >
> > > -     mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS);
> > > +     /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
> > > +     mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
> > >       if (IS_ERR_OR_NULL(mm)) {
> > >               ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
> > >               goto release_task;
> > >       }
> > >
> > > +     /*
> > > +      * Require CAP_SYS_NICE for influencing process performance. Note 
> > > that
> > > +      * only non-destructive hints are currently supported.
> > > +      */
> > > +     if (!capable(CAP_SYS_NICE)) {
> > > +             ret = -EPERM;
> > > +             goto release_task;
> >
> > mmput?
> 
> Ouch! Thanks for pointing it out! Will include in the next respin.
> 

With the fix, feel free to add:

        Acked-by: David Rientjes <rient...@google.com>

Thanks Suren!