nvme-core: fix memory leak in dhchap_ctrl_secret

Free dhchap_secret in nvme_ctrl_dhchap_ctrl_secret_store() before we
return when nvme_auth_generate_key() returns error.

Fixes: f50fff7 ("nvme: implement In-Band authentication")
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: Chaitanya Kulkarni

drivers/nvme/host/core.c

@@ -3882,16 +3882,19 @@ static ssize_t nvme_ctrl_dhchap_ctrl_secret_store(struct device *dev,
 		int ret;
 
 		ret = nvme_auth_generate_key(dhchap_secret, &key);
-		if (ret)
+		if (ret) {
+			kfree(dhchap_secret);
 			return ret;
+		}
 		kfree(opts->dhchap_ctrl_secret);
 		opts->dhchap_ctrl_secret = dhchap_secret;
 		ctrl_key = ctrl->ctrl_key;
 		mutex_lock(&ctrl->dhchap_auth_mutex);
 		ctrl->ctrl_key = key;
 		mutex_unlock(&ctrl->dhchap_auth_mutex);
 		nvme_auth_free_key(ctrl_key);
-	}
+	} else
+		kfree(dhchap_secret);
 	/* Start re-authentication */
 	dev_info(ctrl->device, "re-authenticating controller\n");
 	queue_work(nvme_wq, &ctrl->dhchap_auth_work);