mailbox: zynq-ipi: fix error handling while device_register() fails

[ Upstream commit a6792a0 ]

If device_register() fails, it has two issues:
1. The name allocated by dev_set_name() is leaked.
2. The parent of device is not NULL, device_unregister() is called
   in zynqmp_ipi_free_mboxes(), it will lead a kernel crash because
   of removing not added device.

Call put_device() to give up the reference, so the name is freed in
kobject_cleanup(). Add device registered check in zynqmp_ipi_free_mboxes()
to avoid null-ptr-deref.

Fixes: 4981b82 ("mailbox: ZynqMP IPI mailbox controller")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mailbox/zynqmp-ipi-mailbox.c

@@ -493,6 +493,7 @@ static int zynqmp_ipi_mbox_probe(struct zynqmp_ipi_mbox *ipi_mbox,
 	ret = device_register(&ipi_mbox->dev);
 	if (ret) {
 		dev_err(dev, "Failed to register ipi mbox dev.\n");
+		put_device(&ipi_mbox->dev);
 		return ret;
 	}
 	mdev = &ipi_mbox->dev;
@@ -619,7 +620,8 @@ static void zynqmp_ipi_free_mboxes(struct zynqmp_ipi_pdata *pdata)
 		ipi_mbox = &pdata->ipi_mboxes[i];
 		if (ipi_mbox->dev.parent) {
 			mbox_controller_unregister(&ipi_mbox->mbox);
-			device_unregister(&ipi_mbox->dev);
+			if (device_is_registered(&ipi_mbox->dev))
+				device_unregister(&ipi_mbox->dev);
 		}
 	}
 }