Re: [PATCH] binder: Use %p for pointer formatting

[Sebastian Andrzej Siewior]

On 2026-09-24 22:17:06 [+0000], Carlos Llamas wrote:
> On Fri, Sep 18, 2026 at 12:30:08PM +0200, Sebastian Andrzej Siewior wrote:
> > Commit 8ca86f1639ec5 ("binder: replace "%p" with "%pK"") introduced the
> > %pK modifier in order not to leak kernel pointer.
> > Since commit ad67b74d2469d ("printk: hash addresses printed with %p")
> > pointers are hashed by default and the behaviour can be controller by
> > `hash_pointers' boot argument.
> > Commit 57483a362741e ("binder: Create safe versions of binder log
> > files") introduced a hashed version while preserving the other interface
> > where pointers are returned. This interface is for debugging of memory
> > leaks. Ideally it would provide just one interface without leaking
> > pointers.
> 
> These binder_log files is a different thing. These are userspace
> pointers.

It looks like the reveal points, I wasn't aware that those are userspace
pointers.

> > The policy on %p is to not introduce new ones. Rather then removing the
> > pointer output make it use %p.
> 
> IIUC, the policy is to use %pK for seq_printf() files exposed to users.
> This is the relevant section from printk-formats.rst:
> 
>  | If (and only if) you are printing addresses as a content of a virtual file in
>  | e.g. procfs or sysfs (using e.g. seq_printf(), not printk()) read by a
>  | userspace process, use the %pK modifier described below instead of %p or %px.
> 
> Has this changed?

I am working on getting rid of %pK.

> > 
> > Cc: Tiffany Y. Yang <ynaffit@xxxxxxxxxx>
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> > ---
> >  drivers/android/binder.c | 4 ++--
> 
> This file is now deleted anyway.

And with it the %pK usage?

> 
> Cheers,

Sebastian