linux-kernel - Re: [PATCH] vsprintf: Fix %pK with kptr

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Message-ID: <YgOrIOLrSfrKE9JO@smile.fi.intel.com>
Date:   Wed, 9 Feb 2022 13:53:04 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] vsprintf: Fix %pK with kptr_restrict == 0

On Tue, Feb 08, 2022 at 02:51:39PM +0100, Petr Mladek wrote:
> On Thu 2022-01-27 11:11:02, Christophe Leroy wrote:

...

> Instead, I would create:
> 
> /*
>  * default is to _not_ leak addresses, so hash before printing,
>  * unless no_hash_pointers is specified on the command line.
>  */
> static noinline_for_stack
> char *default_pointer(const char *fmt, char *buf, char *end, void *ptr,
> 		      struct printf_spec spec)
> {
> 	if (unlikely(no_hash_pointers))
> 		return pointer_string(buf, end, ptr, spec);
> 
> 	return ptr_to_id(buf, end, ptr, spec);
> }
> 
> and use it in both hash_pointer() and pointer().

I like this idea.

-- 
With Best Regards,
Andy Shevchenko