Messages in this thread Patch in this message | | | Date | Mon, 23 Jan 2012 15:40:58 -0800 | From | Greg KH <> | Subject | [12/27] x86: Fix mmap random address range |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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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; }
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