Messages in this thread Patch in this message | | | From | Ludwig Nussel <> | Subject | [PATCH] fix mmap random address range on x86 (try2) | Date | Mon, 28 Feb 2011 15:53:03 +0100 |
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On x86 casting the unsigned int result of get_random_int() to long may result in a negative value. On x86 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 commit 675a081 in January 2008.
Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de> --- arch/x86/mm/mmap.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 1dab519..f927429 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; } -- 1.7.3.4
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