What if I want to build a string in a loop, and pass it to printf? The new
compilier wouldn't be 100% backword compatible with gcc. Or am I missing
something?

-----Original Message-----
From: VULN-DEV List [mailto:VULN-DEVSECURITYFOCUS.COM]On Behalf Of
Makoto Iwamura
Sent: Wednesday, April 04, 2001 11:23 AM
To: VULN-DEVSECURITYFOCUS.COM
Subject: Re: GCC extension for protecting applications from format
string attacks

Fergus Henderson wrote:
>On 02-Apr-2001, Crispin Cowan <crispinwirex.com> wrote:
>
>> Ok. Assuming that <mark> is some kind of encoding such that protectec
>> printf can determine whether it is there or not, and standard printf
>> is not confused by <mark> being present, then this seems to have solved
>> the 2-way compatibility problem. Now you're only stuck with the usual
>> problems incurred by writing to the code segment :-)
>>
>> These would be:
>>
>> * Can't ROM the code. [...]
>> * No recursion. [...]
>> * Questionable reentrancy. [...]
>
>I think you misunderstood again. The mark is put in the code segment
>at compile time. It is not modified at runtime. So it doesn't have
>any of those problems that you mention.

Yes, an argument count is decided and put in the code segument at
the time when the calling function is compiled.

Thanks for your answering instead of me.

--
Makoto Iwamura <iwamuramuraoka.info.waseda.ac.jp>
Muraoka Laboratory, Dept. of Information & Computer Science
Graduate School of Science & Engineering, Waseda University

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]