linux-kernel - Re: [PATCH 1/4] lib/vsprintf.c: handle invalid format specifiers more robustly

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Message-ID: <87bncmfgm0.fsf@rasmusvillemoes.dk>
Date:	Mon, 28 Sep 2015 22:12:23 +0200
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 1/4] lib/vsprintf.c: handle invalid format specifiers more robustly

On Mon, Sep 28 2015, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

>>  		/*
>> -		 * Since %n poses a greater security risk than 
>> utility, treat
>> -		 * it as an invalid format specifier. Warn about its 
>> use so
>> -		 * that new instances don't get added.
>> +		 * Since %n poses a greater security risk than
>
> Any reason to wrap first string?

I just hit M-q in emacs and let that take care of somewhat sane
wrapping. I don't play diff golf.

>> +			/*
>> +			 * Presumably the arguments passed gcc's 
>> type
>> +			 * checking, but there is no safe or sane 
>> way
>> +			 * for us to continue parsing the format and
>> +			 * fetching from the va_list; the remaining
>> +			 * specifiers and arguments would be out of
>> +			 * sync.
>
> Could we use wider strings in the commentary here?

Ditto.

Rasmus
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