event/dlb2: add shift value check in sparse dequeue

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.

Coverity issue: 376527
Fixes: e697f35dbdd1 ("event/dlb2: update rolling mask used for dequeue")
Cc: stable@dpdk.org
Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>

diff --git a/drivers/event/dlb2/dlb2.c b/drivers/event/dlb2/dlb2.c
index 09abdd166035e79f8d215514fcedb034db15d9d5..7789dd74e0a452be81a71f6a8162fb3ddebf9664 100644 (file)
--- 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],