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.
> }
>
> static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
>
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