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Date: Fri, 14 Nov 2003 11:31:04 +0800
From: Adrian Hoe <adrianhoe@nowhere.com>
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Subject: Re: C's trikery semantic opens up backdoor in new Linux kernel
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Date: 2003-11-14T11:31:04+08:00
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Wes Groleau wrote:

> 
>> Yeah, = and == make a lot of difference. It supposed to be:
>>
>> someone == root
>>
>> but it turned up to be
>>
>> some = root
> 
> 
> Correction: it was intended to LOOK LIKE
> 
> someone == root
> 
> but the
> 
> some = root
> 
> was intentional, and the CM mechanism was cheated
> to get it in without tracing it to who did it.
> 
> 


According to my understanding of the article, it was intended like this:

if someone == root

but the statement was deliberately/mistakenly written like this:

if some = root



Consider this:

int main()
{

    int root = 1;
    int someone;

    someone=root;

    if (someone==root) {
       printf ("Some is root!\n");
    }

    if (someone=root) {     /* this cannot happen in Ada */
       printf ("Some has become root!\n");
    }
}



-- 
Adrian Hoe
m a i l b o x AT a d r i a n h o e . c o m