On Wed, 22 Oct 2014 09:42:46 +0400 Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> wrote:
> On 10/21/2014 10:15 PM, Sasha Levin wrote:
> > hstate_sizelog() would shift left an int rather than long, triggering
> > undefined behaviour and passing an incorrect value when the requested
> > page size was more than 4GB, thus breaking >4GB pages.
>
> >
> > Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> > ---
> > include/linux/hugetlb.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> > index 65e12a2..57e0dfd 100644
> > --- a/include/linux/hugetlb.h
> > +++ b/include/linux/hugetlb.h
> > @@ -312,7 +312,8 @@ static inline struct hstate *hstate_sizelog(int page_size_log)
> > {
> > if (!page_size_log)
> > return &default_hstate;
> > - return size_to_hstate(1 << page_size_log);
> > +
> > + return size_to_hstate(1UL << page_size_log);
>
> That still could be undefined on 32-bits. Either use 1ULL or reduce SHM_HUGE_MASK on 32bits.
>
But
struct hstate *size_to_hstate(unsigned long size)
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