Commit 3e19086f authored by Kees Cook's avatar Kees Cook
Browse files

overflow: Adjust check_*_overflow() kern-doc to reflect results 



The check_*_overflow() helpers will return results with potentially
wrapped-around values. These values have always been checked by the
selftests, so avoid the confusing language in the kern-doc. The idea of
"safe for use" was relative to the expectation of whether or not the
caller wants a wrapped value -- the calculation itself will always follow
arithmetic wrapping rules.

Reviewed-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent adeb0436

include/linux/overflow.h

+9 −12
Original line number Diff line number Diff line
@@ -57,11 +57,10 @@ static inline bool __must_check __must_check_overflow(bool overflow) 
 * @b: second addend

 * @d: pointer to store sum

 *

 * Returns 0 on success.

 * Returns true on wrap-around, false otherwise.

 *

 * *@d holds the results of the attempted addition, but is not considered

 * "safe for use" on a non-zero return value, which indicates that the

 * sum has overflowed or been truncated.

 * *@d holds the results of the attempted addition, regardless of whether

 * wrap-around occurred.

 */

#define check_add_overflow(a, b, d)	\

	__must_check_overflow(__builtin_add_overflow(a, b, d))
@@ -72,11 +71,10 @@ static inline bool __must_check __must_check_overflow(bool overflow) 
 * @b: subtrahend; value to subtract from @a

 * @d: pointer to store difference

 *

 * Returns 0 on success.

 * Returns true on wrap-around, false otherwise.

 *

 * *@d holds the results of the attempted subtraction, but is not considered

 * "safe for use" on a non-zero return value, which indicates that the

 * difference has underflowed or been truncated.

 * *@d holds the results of the attempted subtraction, regardless of whether

 * wrap-around occurred.

 */

#define check_sub_overflow(a, b, d)	\

	__must_check_overflow(__builtin_sub_overflow(a, b, d))
@@ -87,11 +85,10 @@ static inline bool __must_check __must_check_overflow(bool overflow) 
 * @b: second factor

 * @d: pointer to store product

 *

 * Returns 0 on success.

 * Returns true on wrap-around, false otherwise.

 *

 * *@d holds the results of the attempted multiplication, but is not

 * considered "safe for use" on a non-zero return value, which indicates

 * that the product has overflowed or been truncated.

 * *@d holds the results of the attempted multiplication, regardless of whether

 * wrap-around occurred.

 */

#define check_mul_overflow(a, b, d)	\

	__must_check_overflow(__builtin_mul_overflow(a, b, d))