| From 9af0c7a6fa860698d080481f24a342ba74b68982 Mon Sep 17 00:00:00 2001 |
| From: Ludwig Nussel <ludwig.nussel@suse.de> |
| Date: Tue, 15 Nov 2011 14:46:46 -0800 |
| Subject: x86: Fix mmap random address range |
| |
| From: Ludwig Nussel <ludwig.nussel@suse.de> |
| |
| commit 9af0c7a6fa860698d080481f24a342ba74b68982 upstream. |
| |
| 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: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: harvey.harrison@gmail.com |
| Cc: "H. Peter Anvin" <hpa@zytor.com> |
| Cc: Harvey Harrison <harvey.harrison@gmail.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Link: http://lkml.kernel.org/r/201111152246.pAFMklOB028527@wpaz5.hot.corp.google.com |
| Signed-off-by: Ingo Molnar <mingo@elte.hu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| arch/x86/mm/mmap.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/arch/x86/mm/mmap.c |
| +++ b/arch/x86/mm/mmap.c |
| @@ -87,9 +87,9 @@ 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; |
| } |
