Message-ID: <43984595.1090406@labri.fr>
Date: Thu, 08 Dec 2005 15:39:17 +0100
From: Emmanuel Fleury <emmanuel.fleury@labri.fr>
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To: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: How to enable/disable security features on mmap() ?
References: <43983EBE.2080604@labri.fr> <1134051272.2867.63.camel@laptopd505.fenrus.org> <43984154.5050502@labri.fr>
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I guess that setting the variable randomize_va_space to 0 just remove
the stack pointer (sp) randomization.

Seen in arch/i386/kernel/process.c:

unsigned long arch_align_stack(unsigned long sp)
{
        if (randomize_va_space)
                sp -= get_random_int() % 8192;
        return sp & ~0xf;
}

Why not having defined this as a CONFIG_STACK_RANDOMIZATION variables
(you have some need to avoid to use it in the case of the Crusoe processor:

Seen in karch/i386/ernel/cpu/transmeta.c:

#ifdef CONFIG_SYSCTL
        /* randomize_va_space slows us down enormously;
           it probably triggers retranslation of x86->native bytecode */
        randomize_va_space = 0;
#endif

Regards
-- 
Emmanuel Fleury

Elegance is not optional.
  -- Richard O'Keefe
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