Messages in this thread | | | Date | Mon, 28 Feb 2011 08:42:22 -0800 | From | Randy Dunlap <> | Subject | Re: [PATCH] fix mmap random address range on x86 (try2) |
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On Mon, 28 Feb 2011 15:53:03 +0100 Ludwig Nussel wrote:
> 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; > } > --
Is there a test case for this? Can it be tested/checked/observed?
thanks, --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***
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