Re: [PATCH v2 1/2] vsprintf: Don't leak pointers for %ps without KALLSYMS enabled

[Petr Mladek <pmladek@suse.com>]

On Mon 2026-08-31 15:30:21, Sebastian Andrzej Siewior wrote:
> On 2026-08-27 11:51:00 [+0200], Petr Mladek wrote:
> > 
> > I think that it is a matter of taste. I could understand that
> > "(unknown)" might look more obvious to some people.
> > 
> > I would still prefer the hashed pointer. It make it consistent with
> > %p handling. Both print addresses in this case.
> 
> For %p expect a pointer, for %pS you expect a name.
> 
> > The motivation for the hash in %p is that it is slightly more useful
> > than a static string, e.g. "(address)" or "(pointer)". The hash allows
> > to match the same addresses. It is not 100% reliable but better
> > than nothing.
> 
> but is this helpful?
> 
> > Also the hash makes it more obvious the connection with "no_hash_pointer"
> > option.
> 
> Assuming you know about the no_hash_pointer. And then you get a
> randomized pointer. Enabling kallsym would be a _bigger_ help than
> rebooting with no_hash_pointer.
> 
> > IMHO, the only drawback is that people might confuse the hash with
> > a real value. But it is easier on 64-bit systems because the higher
> > 32-bits are zeros.
> 
> That, too. Do you continue to insist on this hashed pointer output here?

I do not insist on it. IMHO, this does not have a good solution.
I wish we got feedback from more people.

Let's give it few more days. The merge window has just ended.
People might have more time to go through pending mails.

Best Regards,
Petr