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authorLudwig Nussel <ludwig.nussel@suse.de>2011-11-15 14:46:46 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-18 07:31:58 -0800
commit0248fedcdb0982fc15246ff23a7b926f592258d5 (patch)
treeffafcd3eb013be74a2b9e503ec396baf67b6ee31
parent8d0120df91823df951facd3527e9f148b24e78f3 (diff)
x86: Fix mmap random address range
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>
-rw-r--r--arch/x86/mm/mmap.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 1dab5194fd9d..f927429d07ca 100644
--- 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;
}