On Fri, 10 May 2019 18:32:58 +0200
Martin Schwidefsky <schwidef...@de.ibm.com> wrote:
> On Fri, 10 May 2019 12:24:01 -0400
> Steven Rostedt <rost...@goodmis.org> wrote:
>
> > On Fri, 10 May 2019 10:42:13 +0200
> > Petr Mladek <pmla...@suse.com> wrote:
> >
> > > static const char *check_pointer_msg(const void *ptr)
> > > {
> > > - char byte;
> > > -
> > > if (!ptr)
> > > return "(null)";
> > >
> > > - if (probe_kernel_address(ptr, byte))
> > > + if ((unsigned long)ptr < PAGE_SIZE || IS_ERR_VALUE(ptr))
> > > return "(efault)";
> > >
> >
> >
> > < PAGE_SIZE ?
> >
> > do you mean: < TASK_SIZE ?
>
> The check with < TASK_SIZE would break on s390. The 'ptr' is
> in the kernel address space, *not* in the user address space.
> Remember s390 has two separate address spaces for kernel/user
> the check < TASK_SIZE only makes sense with a __user pointer.
>
So we allow this to read user addresses? Can't that cause a fault?
If the condition is true, we return "(efault)".
-- Steve
