igc: Check if num of q_vectors is smaller than max before array access

Ensure that the adapter->q_vector[MAX_Q_VECTORS] array isn't accessed
beyond its size. It was fixed by using a local variable num_q_vectors
as a limit for loop index, and ensure that num_q_vectors is not bigger
than MAX_Q_VECTORS.
Suggested-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_main.c

@@ -5125,6 +5125,7 @@ static irqreturn_t igc_msix_ring(int irq, void *data)
  */
 static int igc_request_msix(struct igc_adapter *adapter)
 {
+	unsigned int num_q_vectors = adapter->num_q_vectors;
 	int i = 0, err = 0, vector = 0, free_vector = 0;
 	struct net_device *netdev = adapter->netdev;
 
@@ -5133,7 +5134,13 @@ static int igc_request_msix(struct igc_adapter *adapter)
 	if (err)
 		goto err_out;
 
-	for (i = 0; i < adapter->num_q_vectors; i++) {
+	if (num_q_vectors > MAX_Q_VECTORS) {
+		num_q_vectors = MAX_Q_VECTORS;
+		dev_warn(&adapter->pdev->dev,
+			 "The number of queue vectors (%d) is higher than max allowed (%d)\n",
+			 adapter->num_q_vectors, MAX_Q_VECTORS);
+	}
+	for (i = 0; i < num_q_vectors; i++) {
 		struct igc_q_vector *q_vector = adapter->q_vector[i];
 
 		vector++;