Re: [PATCH] mm, hugetlb: correct bit shift in hstate_sizelog
From: Andrey Ryabinin <hidden>
Date: 2014-10-22 05:42:51
Also in:
lkml
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.
quoted hunk ↗ jump to hunk
Signed-off-by: Sasha Levin <redacted> --- 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)
-- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>