Fix: prevent divide-by-zero in mt_srss_init (#1298)

Add validation to check if nb_rx_q is zero before it can be used in
division. If nb_rx_q is zero, return -EINVAL with error message.

This prevents the divide-by-zero at line 459 where srss->nb_rx_q /
srss->schs_cnt could fail if schs_cnt becomes zero (which happens when
nb_rx_q is zero).

Author: soopel

lib/src/datapath/mt_shared_rss.c

@@ -454,6 +454,13 @@ int mt_srss_init(struct mtl_main_impl* impl) {
       mt_srss_uinit(impl);
       return -ENOMEM;
     }
+
+    /* making sure schs_cnt is not zero to prevent divide-by-zero */
+    if (!srss->schs_cnt) {
+      err("%s(%d), schs_cnt is zero\n", __func__, port);
+      mt_srss_uinit(impl);
+      return -EINVAL;
+    }
     mt_sch_mask_t sch_mask = MT_SCH_MASK_ALL;
     uint16_t q_idx = 0;
     uint16_t q_per_sch = srss->nb_rx_q / srss->schs_cnt;