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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: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
pull/981/head
Kees Cook 2024-01-29 10:21:58 -08:00
parent adeb04362d
commit 3e19086fb5
1 changed files with 9 additions and 12 deletions
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21
include/linux/overflow.h
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@ -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))