xen-netfront: update num_queues to real created

Sometimes xennet_create_queues() may failed to created all requested
queues, we need to update num_queues to real created to avoid NULL
pointer dereference.

Orabug: 22069665

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index b9c637a0036b5a8f2df110a27a2aadfc817114e3..5dc3b8125d09015a073cf6596ad8417633c916e6 100644 (file)
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1704,19 +1704,19 @@ static void xennet_destroy_queues(struct netfront_info *info)
 }
 
 static int xennet_create_queues(struct netfront_info *info,
-                               unsigned int num_queues)
+                               unsigned int *num_queues)
 {
        unsigned int i;
        int ret;
 
-       info->queues = kcalloc(num_queues, sizeof(struct netfront_queue),
+       info->queues = kcalloc(*num_queues, sizeof(struct netfront_queue),
                               GFP_KERNEL);
        if (!info->queues)
                return -ENOMEM;
 
        rtnl_lock();
 
-       for (i = 0; i < num_queues; i++) {
+       for (i = 0; i < *num_queues; i++) {
                struct netfront_queue *queue = &info->queues[i];
 
                queue->id = i;
@@ -1726,7 +1726,7 @@ static int xennet_create_queues(struct netfront_info *info,
                if (ret < 0) {
                        dev_warn(&info->netdev->dev,
                                 "only created %d queues\n", i);
-                       num_queues = i;
+                       *num_queues = i;
                        break;
                }
 
@@ -1736,11 +1736,11 @@ static int xennet_create_queues(struct netfront_info *info,
                        napi_enable(&queue->napi);
        }
 
-       netif_set_real_num_tx_queues(info->netdev, num_queues);
+       netif_set_real_num_tx_queues(info->netdev, *num_queues);
 
        rtnl_unlock();
 
-       if (num_queues == 0) {
+       if (*num_queues == 0) {
                dev_err(&info->netdev->dev, "no queues\n");
                return -EINVAL;
        }
@@ -1786,7 +1786,7 @@ static int talk_to_netback(struct xenbus_device *dev,
        if (info->queues)
                xennet_destroy_queues(info);
 
-       err = xennet_create_queues(info, num_queues);
+       err = xennet_create_queues(info, &num_queues);
        if (err < 0)
                goto destroy_ring;