Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH v5 1/3] overflow: Adjust check_*_overflow() kern-doc to reflect results | Date | Wed, 7 Feb 2024 07:24:18 -0800 |
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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> Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/overflow.h | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 7b5cf4a5cd19..4e741ebb8005 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -57,11 +57,9 @@ static inline bool __must_check __must_check_overflow(bool overflow) * @b: second addend * @d: pointer to store sum * - * Returns 0 on success. + * Returns 0 on success, 1 on wrap-around. * - * *@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, which may wrap-around. */ #define check_add_overflow(a, b, d) \ __must_check_overflow(__builtin_add_overflow(a, b, d)) @@ -72,11 +70,9 @@ 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 0 on success, 1 on wrap-around. * - * *@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, which may wrap-around. */ #define check_sub_overflow(a, b, d) \ __must_check_overflow(__builtin_sub_overflow(a, b, d)) @@ -87,11 +83,9 @@ static inline bool __must_check __must_check_overflow(bool overflow) * @b: second factor * @d: pointer to store product * - * Returns 0 on success. + * Returns 0 on success, 1 on wrap-around. * - * *@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, which may wrap-around. */ #define check_mul_overflow(a, b, d) \ __must_check_overflow(__builtin_mul_overflow(a, b, d)) -- 2.34.1
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