linux-kernel - Re: [PATCH] x86: Don't randomize stack unless current->personality permits it

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Date:	Sat, 15 Jul 2006 23:58:10 -0400
From:	Chuck Ebbert <76306.1226@...puserve.com>
To:	Al Boldi <a1426z@...ab.com>
Cc:	Frank van Maarseveen <frankvm@...nkvm.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: [PATCH] x86: Don't randomize stack unless
  current->personality permits it

In-Reply-To: <200607151709.45870.a1426z@...ab.com>

On Sat, 15 Jul 2006 17:09:45 +0300, Al Boldi wrote:

> Randomization on.  Executable runs with 8x blips/hits.
> Randomization off.  Executable runs without blips/hits.
> With randomization off, a mere rename causes an 8x-slowdown to occur.  Run 
> this renamed executable through sh -c ./tstExec, and the slowdown 
> disappears.  Really weired :)

Does this help at all?  I don't have a space heater^W^WPentium IV
to test on.

--- 2.6.18-rc1-nb.orig/arch/i386/kernel/process.c
+++ 2.6.18-rc1-nb/arch/i386/kernel/process.c
@@ -890,5 +890,5 @@ unsigned long arch_align_stack(unsigned 
 {
 	if (randomize_va_space)
 		sp -= get_random_int() % 8192;
-	return sp & ~0xf;
+	return sp & ~0x7f;
 }
-- 
Chuck
 "You can't read a newspaper if you can't read."  --George W. Bush
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