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Date: Thu, 15 Mar 2018 13:07:17 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "Tobin C . Harding" <me@tobin.cc>, Joe Perches <joe@perches.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid
 pointers
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On Thu, 15 Mar 2018 16:07:54 +0100
Petr Mladek <pmladek@suse.com> wrote:

> Good point. The following should do the job:
> 
> static const char *check_pointer_access(const void *ptr)
> {
> 	char c;
> 
> 	if (!ptr)
> 		return "(null)";
> 
> 	if ((unsigned long)ptr < TASK_SIZE || probe_kernel_address(ptr, c))

Please don't.

-- Steve

> 		return "(efault)";
> 
> 	return 0;
> }