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Date: Tue, 16 Apr 2013 22:04:49 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: Segfaults probably caused by DEBUG code in memory.c (was: Segfault for linux-x86-native with -DDEBUG added)
On 16 Apr, 2013, at 21:56 , "jfoug" <jfoug@....net> wrote:
> From: magnum Sent: Tuesday, April 16, 2013 14:32
>> Not the same thing. In the normal non-debug code we obviously must do it, because we are re-using one large >memory block for many smaller blocks. That is one of mem_alloc_tiny's two reasons to exist.
>
> No, look at the very bottom of mem_alloc_tiny. That code happens when a
> huge block is requested (larger than MEM_ALLOC_SIZE). In that case,
> mem_alloc_tiny allocates a specific block JUST for this object, without
> impacting the buffer object at all.
>
> That code is really what you wanted to to in DEBUG mode, but doing it for
> every block.
Ah, you're right. This is obviously for MEM_ALIGN_CACHE and stuff like that.
> In hindsight, in debug mode, you might have gotten the same results by doing
> this:
>
> #if DEBUG
> #undef MEM_ALLOC_SIZE
> #define MEM_ALLOC_SIZE 0
> #endif
>
> I think you would have gotten the same results. NOTE I have not tested that
> hypothesis at all.
Probably also true, but I won't try it cause it will be slightly slower :-)
magnum
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