diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
index 6a55aac0c60f..63086f90bbf8 100644
--- a/drivers/ata/libahci_platform.c
+++ b/drivers/ata/libahci_platform.c
@@ -421,14 +421,24 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
 		}
 	}
 
-	hpriv->nports = child_nodes = of_get_child_count(dev->of_node);
+	/*
+	 * Too many sub-nodes most likely means having something wrong with
+	 * the firmware.
+	 */
+	child_nodes = of_get_child_count(dev->of_node);
+	if (child_nodes > AHCI_MAX_PORTS) {
+		rc = -EINVAL;
+		goto err_out;
+	}
 
 	/*
 	 * If no sub-node was found, we still need to set nports to
 	 * one in order to be able to use the
 	 * ahci_platform_[en|dis]able_[phys|regulators] functions.
 	 */
-	if (!child_nodes)
+	if (child_nodes)
+		hpriv->nports = child_nodes;
+	else
 		hpriv->nports = 1;
 
 	hpriv->phys = devm_kcalloc(dev, hpriv->nports, sizeof(*hpriv->phys), GFP_KERNEL);