linux-kernel - Re: [PATCH 1/2] vsprintf: distinguish between (null), (err) and (invalid) pointer derefs

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Message-ID: <1520429370.10722.467.camel@linux.intel.com>
Date:   Wed, 07 Mar 2018 15:29:30 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Adam Borowski <kilobyte@...band.pl>,
        Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>, Joe Perches <joe@...ches.com>,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>
Subject: Re: [PATCH 1/2] vsprintf: distinguish between (null), (err) and
 (invalid) pointer derefs

On Tue, 2018-03-06 at 19:11 +0100, Adam Borowski wrote:
> Attempting to print an object pointed to by a bad (usually ERR_PTR)
> pointer
> is a not so surprising error.  Our code handles them inconsistently:
>  * two places print (null) if ptr<PAGE_SIZE
>  * one place prints (null) if abs(ptr)<PAGE_SIZE
>  * one place prints (null) only if !ptr
> 
> Obviously, saying (null) for a small but non-0 value is misleading.
> Thus, let's print:
>  * (null) for exactly 0
>  * (err) if last page && abs(ptr)<=MAX_ERRNO
>  * (invalid) otherwise

Ah, and last but not least thing.
Where are the test cases?

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy