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

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Message-ID: <1521119224.10722.664.camel@linux.intel.com>
Date:   Thu, 15 Mar 2018 15:07:04 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        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>
Subject: Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid
 pointers

On Thu, 2018-03-15 at 16:58 +0900, Sergey Senozhatsky wrote:
> On (03/14/18 15:09), Petr Mladek wrote:
> 


> >  char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> >  	      struct printf_spec spec)
> >  {
> > +	static const char data_access_fmt[] =
> > "RrhbMmIiEUVNadCDgGO";
> >  	const int default_width = 2 * sizeof(void *);
> > +	const char *err_msg = NULL;
> > +
> > +	/* Prevent silent crash when this is called under
> > logbuf_lock. */
> > +	if (*fmt && strchr(data_access_fmt, *fmt) != NULL)
> > +		err_msg = check_pointer_access(ptr);
> 
> Agree with Rasmus, I think switch() is easier.
> 

One more to the same.

Though need to add that we also have to append / update some comment to
keep these lists synchronized (in Documentation, around pointer() and
here)

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