RE: [PATCH] vsprintf: Do not break early boot with probing addresses

David Laight
2019-05-13T08:52:41Z

From: christophe leroy
> Sent: 10 May 2019 18:35
> Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
> > On Fri, 10 May 2019 10:42:13 +0200
> > Petr Mladek <pmladek@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)";

"efault" looks a bit like a spellling mistake for "default".

> > < PAGE_SIZE ?
> >
> > do you mean: < TASK_SIZE ?
>
> I guess not.
>
> Usually, < PAGE_SIZE means NULL pointer dereference (via the member of a
> struct)

Maybe the caller should pass in a short buffer so that you can return
"(err-%d)" or "(null+%#x)" ?

David

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