igb: 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.

Fixes: 047e0030 ("igb: add new data structure for handling interrupts and NAPI")
Signed-off-by: NAleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: NGrzegorz Siwik <grzegorz.siwik@intel.com>
Reviewed-by: NArkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Reviewed-by: NSlawomir Laba <slawomirx.laba@intel.com>
Reviewed-by: NSylwester Dziedziuch <sylwesterx.dziedziuch@intel.com>
Reviewed-by: NMateusz Palczewski <mateusz.placzewski@intel.com>
Tested-by: NTony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -931,6 +931,7 @@ static void igb_configure_msix(struct igb_adapter *adapter)
  **/
 static int igb_request_msix(struct igb_adapter *adapter)
 {
+	unsigned int num_q_vectors = adapter->num_q_vectors;
 	struct net_device *netdev = adapter->netdev;
 	int i, err = 0, vector = 0, free_vector = 0;
 
@@ -939,7 +940,13 @@ static int igb_request_msix(struct igb_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 igb_q_vector *q_vector = adapter->q_vector[i];
 
 		vector++;