Commit 710bb68c authored by Matthias Goergens's avatar Matthias Goergens Committed by Andrew Morton
Browse files

hugetlb_encode.h: fix undefined behaviour (34 << 26) 

Left-shifting past the size of your datatype is undefined behaviour in C. 
The literal 34 gets the type `int`, and that one is not big enough to be
left shifted by 26 bits.

An `unsigned` is long enough (on any machine that has at least 32 bits for
their ints.)

For uniformity, we mark all the literals as unsigned.  But it's only
really needed for HUGETLB_FLAG_ENCODE_16GB.

Thanks to Randy Dunlap for an initial review and suggestion.

Link: https://lkml.kernel.org/r/20220905031904.150925-1-matthias.goergens@gmail.com


Signed-off-by: default avatarMatthias Goergens <matthias.goergens@gmail.com>
Acked-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c274cd5c

include/uapi/asm-generic/hugetlb_encode.h

+13 −13
Original line number Diff line number Diff line
@@ -20,18 +20,18 @@ 
#define HUGETLB_FLAG_ENCODE_SHIFT	26

#define HUGETLB_FLAG_ENCODE_MASK	0x3f



#define HUGETLB_FLAG_ENCODE_16KB	(14 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_32MB	(25 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512MB	(29 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16KB	(14U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_64KB	(16U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512KB	(19U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1MB		(20U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2MB		(21U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_8MB		(23U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16MB	(24U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_32MB	(25U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_256MB	(28U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512MB	(29U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1GB		(30U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2GB		(31U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16GB	(34U << HUGETLB_FLAG_ENCODE_SHIFT)



#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */

tools/include/asm-generic/hugetlb_encode.h

+13 −13
Original line number Diff line number Diff line
@@ -20,18 +20,18 @@ 
#define HUGETLB_FLAG_ENCODE_SHIFT	26

#define HUGETLB_FLAG_ENCODE_MASK	0x3f



#define HUGETLB_FLAG_ENCODE_16KB	(14 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_32MB	(25 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512MB	(29 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16KB	(14U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_64KB	(16U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512KB	(19U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1MB		(20U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2MB		(21U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_8MB		(23U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16MB	(24U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_32MB	(25U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_256MB	(28U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_512MB	(29U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_1GB		(30U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_2GB		(31U << HUGETLB_FLAG_ENCODE_SHIFT)

#define HUGETLB_FLAG_ENCODE_16GB	(34U << HUGETLB_FLAG_ENCODE_SHIFT)



#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */