linux-kernel - Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid pointers

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Message-ID: <1521224375.23017.41.camel@linux.intel.com>
Date:   Fri, 16 Mar 2018 20:19:35 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>, Joe Perches <joe@...ches.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid
 pointers

On Thu, 2018-03-15 at 16:26 +0100, Petr Mladek wrote:
> On Thu 2018-03-15 15:09:03, Andy Shevchenko wrote:
> > On Wed, 2018-03-14 at 15:09 +0100, Petr Mladek wrote:
> > > We already prevent crash when dereferencing some obviously broken
> > > pointers. But the handling is not consistent. Sometimes we print
> > > "(null)"
> > > only for pure NULL pointer, sometimes for pointers in the first
> > > page and 
> > 
> > 
> > > sometimes also for pointers in the last page (error codes).
> > 
> > I still think that printing a hex value of the error code is much
> > better
> > than some odd "(efault)".
> 
> Do you mean (err:0e)? Google gives rather confusing answers for this.

More like "(0xHHHH)" (we have already more than 512 error code numbers.


> I am not super excited about (efault). But it seems to be less
> cryptic and the style is more similar to (null).
> 
> Best Regards,
> Petr

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