From 99db710f768e988e70f1164537bf533a017be24d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 20 Feb 2024 21:16:38 -0800 Subject: refcount: Annotated intentional signed integer wrap-around Mark the various refcount_t functions with __signed_wrap, as we depend on the wrapping behavior to detect the overflow and perform saturation. Silences warnings seen with the LKDTM REFCOUNT_* tests: UBSAN: signed-integer-overflow in ../include/linux/refcount.h:189:11 2147483647 + 1 cannot be represented in type 'int' Reviewed-by: Miguel Ojeda Link: https://lore.kernel.org/r/20240221051634.work.287-kees@kernel.org Signed-off-by: Kees Cook --- include/linux/refcount.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'include/linux/refcount.h') diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 85c6df0d1bef..59b3b752394d 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -136,7 +136,8 @@ static inline unsigned int refcount_read(const refcount_t *r) return atomic_read(&r->refs); } -static inline __must_check bool __refcount_add_not_zero(int i, refcount_t *r, int *oldp) +static inline __must_check __signed_wrap +bool __refcount_add_not_zero(int i, refcount_t *r, int *oldp) { int old = refcount_read(r); @@ -177,7 +178,8 @@ static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r) return __refcount_add_not_zero(i, r, NULL); } -static inline void __refcount_add(int i, refcount_t *r, int *oldp) +static inline __signed_wrap +void __refcount_add(int i, refcount_t *r, int *oldp) { int old = atomic_fetch_add_relaxed(i, &r->refs); @@ -256,7 +258,8 @@ static inline void refcount_inc(refcount_t *r) __refcount_inc(r, NULL); } -static inline __must_check bool __refcount_sub_and_test(int i, refcount_t *r, int *oldp) +static inline __must_check __signed_wrap +bool __refcount_sub_and_test(int i, refcount_t *r, int *oldp) { int old = atomic_fetch_sub_release(i, &r->refs); -- cgit v1.2.3