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

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Message-ID: <1522678523.21176.178.camel@linux.intel.com>
Date:   Mon, 02 Apr 2018 17:15:23 +0300
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, 2018-03-29 at 16:53 +0200, Petr Mladek wrote:
> On Fri 2018-03-16 20:19:35, Andy Shevchenko wrote:
> > On Thu, 2018-03-15 at 16:26 +0100, Petr Mladek wrote:
> > > On Thu 2018-03-15 15:09:03, Andy Shevchenko wrote:

> > > > 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.
> 
> Hmm, I have never seen the error code in this form.

We have limited space to print it and error numbers currently can be up
to 0xfff (4095). So, I have no better idea how to squeeze them while
thinking that "(efault)" is much harder to parse in case of error
pointer.

>  Also google gives
> rather confusing results when searching, for example for "(0x000E)".

It's not primarily for google, though yeah, people would google for
error messages...

Another question is what the format: decimal versus hex for errors.
Maybe just "(-DDDDD)"?

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