[PATCH] event/dlb2: fix invalid shift value

[Jerin Jacob]

On Wed, Mar 2, 2022 at 8:42 PM Timothy McDaniel
<timothy.mcdaniel at intel.com> wrote:
>
> Add a check to ensure that all shift counts are valid.
> Shifting by more than 63 bits may result in undefined behavior, as
> noted during coverity scan.
>
> Fixes: e697f35dbdd1 ("event/dlb2: update rolling mask used for dequeue")
> Coverity issue: 376527


Applied to dpdk-next-net-eventdev/for-main. Thanks


> Signed-off-by: Timothy McDaniel <timothy.mcdaniel at intel.com>
> ---
>  drivers/event/dlb2/dlb2.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/event/dlb2/dlb2.c b/drivers/event/dlb2/dlb2.c
> index 09abdd1660..7789dd74e0 100644
> --- a/drivers/event/dlb2/dlb2.c
> +++ b/drivers/event/dlb2/dlb2.c
> @@ -3916,15 +3916,17 @@ dlb2_hw_dequeue_sparse(struct dlb2_eventdev *dlb2,
>                                                                 &events[num],
>                                                                 &qes[0],
>                                                                 num_avail);
> -                       num += n_iter;
> -                       /* update rolling_mask for vector code support */
> -                       m_rshift = qm_port->cq_rolling_mask >> n_iter;
> -                       m_lshift = qm_port->cq_rolling_mask << (64 - n_iter);
> -                       m2_rshift = qm_port->cq_rolling_mask_2 >> n_iter;
> -                       m2_lshift = qm_port->cq_rolling_mask_2 <<
> +                       if (n_iter != 0) {
> +                               num += n_iter;
> +                               /* update rolling_mask for vector code support */
> +                               m_rshift = qm_port->cq_rolling_mask >> n_iter;
> +                               m_lshift = qm_port->cq_rolling_mask << (64 - n_iter);
> +                               m2_rshift = qm_port->cq_rolling_mask_2 >> n_iter;
> +                               m2_lshift = qm_port->cq_rolling_mask_2 <<
>                                         (64 - n_iter);
> -                       qm_port->cq_rolling_mask = (m_rshift | m2_lshift);
> -                       qm_port->cq_rolling_mask_2 = (m2_rshift | m_lshift);
> +                               qm_port->cq_rolling_mask = (m_rshift | m2_lshift);
> +                               qm_port->cq_rolling_mask_2 = (m2_rshift | m_lshift);
> +                       }
>                 } else { /* !use_scalar */
>                         num_avail = dlb2_recv_qe_sparse_vec(qm_port,
>                                                             &events[num],
> --
> 2.25.1
>