From 6d5d96d57da0e01ef2cdadb3eb5847ab70a1bed4 Mon Sep 17 00:00:00 2001
From: Ludwig Nussel <ludwig.nussel@suse.de>
Date: Thu, 25 Aug 2011 09:46:16 +1000
Subject: [PATCH] On x86_32 casting the unsigned int result of get_random_int()
 to long may result in a negative value.  On x86_32 the range of mmap_rnd()
 therefore was -255 to 255.  The 32bit mode on x86_64 used 0 to 255 as
 intended.

The bug was introduced by 675a081 ("x86: unify mmap_{32|64}.c") in January
2008.

Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 arch/x86/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 4b5ba85eb5c9..845df6835f9f 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -75,9 +75,9 @@ static unsigned long mmap_rnd(void)
 	*/
 	if (current->flags & PF_RANDOMIZE) {
 		if (mmap_is_ia32())
-			rnd = (long)get_random_int() % (1<<8);
+			rnd = get_random_int() % (1<<8);
 		else
-			rnd = (long)(get_random_int() % (1<<28));
+			rnd = get_random_int() % (1<<28);
 	}
 	return rnd << PAGE_SHIFT;
 }
-- 
2.39.5