releases/3.0.18/x86-fix-mmap-random-address-range.patch

   1 From 9af0c7a6fa860698d080481f24a342ba74b68982 Mon Sep 17 00:00:00 2001
   2 From: Ludwig Nussel <ludwig.nussel@suse.de>
   3 Date: Tue, 15 Nov 2011 14:46:46 -0800
   4 Subject: x86: Fix mmap random address range
   5
   6 From: Ludwig Nussel <ludwig.nussel@suse.de>
   7
   8 commit 9af0c7a6fa860698d080481f24a342ba74b68982 upstream.
   9
  10 On x86_32 casting the unsigned int result of get_random_int() to
  11 long may result in a negative value.  On x86_32 the range of
  12 mmap_rnd() therefore was -255 to 255.  The 32bit mode on x86_64
  13 used 0 to 255 as intended.
  14
  15 The bug was introduced by 675a081 ("x86: unify mmap_{32|64}.c")
  16 in January 2008.
  17
  18 Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>
  19 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  20 Cc: harvey.harrison@gmail.com
  21 Cc: "H. Peter Anvin" <hpa@zytor.com>
  22 Cc: Harvey Harrison <harvey.harrison@gmail.com>
  23 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  24 Link: http://lkml.kernel.org/r/201111152246.pAFMklOB028527@wpaz5.hot.corp.google.com
  25 Signed-off-by: Ingo Molnar <mingo@elte.hu>
  26 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  27
  28 ---
  29  arch/x86/mm/mmap.c |    4 ++--
  30  1 file changed, 2 insertions(+), 2 deletions(-)
  31
  32 --- a/arch/x86/mm/mmap.c
  33 +++ b/arch/x86/mm/mmap.c
  34 @@ -87,9 +87,9 @@ static unsigned long mmap_rnd(void)
  35         */
  36         if (current->flags & PF_RANDOMIZE) {
  37                 if (mmap_is_ia32())
  38 -                       rnd = (long)get_random_int() % (1<<8);
  39 +                       rnd = get_random_int() % (1<<8);
  40                 else
  41 -                       rnd = (long)(get_random_int() % (1<<28));
  42 +                       rnd = get_random_int() % (1<<28);
  43         }
  44         return rnd << PAGE_SHIFT;
  45  }