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Date:      Thu, 22 Feb 2001 16:16:54 +0300 (MSK)
From:      Dmitry Dicky <diwil@eis.ru>
To:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: warning in free():
Message-ID:  <XFMail.010222161654.diwil@eis.ru>
In-Reply-To: <20010222051302.E29126@fw.wintelcom.net>

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Also, if you do something like:

        void *ptr = malloc(size);
        
...
        ptr++;

free() will complain about it. 
Make sure you are not modifying ptr after it has been malloc()ed.


On 22-Feb-01 Alfred Perlstein wrote:
> * Madhavi Suram <madhavis@sasken.com> [010222 05:09] wrote:
>> 
>> Hi
>> 
>> I am running a C program in user space on FreeBSD 3.3 release. I got a
>> warning like this:
>> 
>>      testing in free(): warning: modified (chunk-) pointer.
>> 
>> testing is the name of the executable I am running.
>> 
>> Could anyone tell me what this warning means?  What may be the effect
>> of
>> this code when I shift it to kernel with due modifications? 
> 
> It means you've most likely corrupted your malloc pool, meaning you've
> written past/before the edge of an allocation you've done.
> 
> To fix it start being mor careful with pointers and checking array
> bounds.
> 
> 
> -- 
> -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
> 
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