[ Upstream commit dc7fe518b0493faa0af0568d6d8c2a33c00f58d0 ]
Attempt to use check_shl_overflow() with inputs of unsigned type produces the following compilation warnings.
drivers/infiniband/hw/mlx5/qp.c: In function _set_user_rq_size_: ./include/linux/overflow.h:230:6: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits] _s >= 0 && _s < 8 * sizeof(*d) ? _s : 0; \ ^~ drivers/infiniband/hw/mlx5/qp.c:5820:6: note: in expansion of macro _check_shl_overflow_ if (check_shl_overflow(rwq->wqe_count, rwq->wqe_shift, &rwq->buf_size)) ^~~~~~~~~~~~~~~~~~ ./include/linux/overflow.h:232:26: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits] (_to_shift != _s || *_d < 0 || _a < 0 || \ ^ drivers/infiniband/hw/mlx5/qp.c:5820:6: note: in expansion of macro _check_shl_overflow_ if (check_shl_overflow(rwq->wqe_count, rwq->wqe_shift, &rwq->buf_size)) ^~~~~~~~~~~~~~~~~~ ./include/linux/overflow.h:232:36: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits] (_to_shift != _s || *_d < 0 || _a < 0 || \ ^ drivers/infiniband/hw/mlx5/qp.c:5820:6: note: in expansion of macro _check_shl_overflow_ if (check_shl_overflow(rwq->wqe_count, rwq->wqe_shift,&rwq->buf_size)) ^~~~~~~~~~~~~~~~~~
Fixes: 0c66847793d1 ("overflow.h: Add arithmetic shift helper") Reviewed-by: Bart Van Assche bvanassche@acm.org Acked-by: Kees Cook keescook@chromium.org Signed-off-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/overflow.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h index 40b48e2133cb8..15eb85de92269 100644 --- a/include/linux/overflow.h +++ b/include/linux/overflow.h @@ -36,6 +36,12 @@ #define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T))) #define type_min(T) ((T)((T)-type_max(T)-(T)1))
+/* + * Avoids triggering -Wtype-limits compilation warning, + * while using unsigned data types to check a < 0. + */ +#define is_non_negative(a) ((a) > 0 || (a) == 0) +#define is_negative(a) (!(is_non_negative(a)))
#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW /* @@ -227,10 +233,10 @@ typeof(d) _d = d; \ u64 _a_full = _a; \ unsigned int _to_shift = \ - _s >= 0 && _s < 8 * sizeof(*d) ? _s : 0; \ + is_non_negative(_s) && _s < 8 * sizeof(*d) ? _s : 0; \ *_d = (_a_full << _to_shift); \ - (_to_shift != _s || *_d < 0 || _a < 0 || \ - (*_d >> _to_shift) != _a); \ + (_to_shift != _s || is_negative(*_d) || is_negative(_a) || \ + (*_d >> _to_shift) != _a); \ })
/**