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

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Message-ID: <1522756585.21176.316.camel@linux.intel.com>
Date:   Tue, 03 Apr 2018 14:56:25 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.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>
Subject: Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid
 pointers

On Tue, 2018-04-03 at 13:52 +0200, Petr Mladek wrote:
> On Tue 2018-04-03 10:12:37, Sergey Senozhatsky wrote:
> > On (04/02/18 17:15), Andy Shevchenko wrote:
> > > > 
> > > > 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
> > 
> > 'efault' looks to me like a misspelled 'default', for some reason.
> 
> I wonder if (-efault) would help a bit.

It's 9 characters, not going to satisfy sizeof(void *) * 2 on 32-bit
systems.

> Even better might be (-EFAULT). But then it would be better to use
> (NULL). It already was but it was explicitly changed to the lowercase
> variant by the commit 0f4f81dce93774a447da3c ("vsprintf: factorize
> "(null)" string").

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