[PATCH] serial: 8250_hub6: fix reference leak on failed device registration

[Guangshuo Li]

When platform_device_register() fails in hub6_init(), the embedded
struct device in hub6_device has already been initialized by
device_initialize(), but the failure path returns the error without
dropping the device reference for the current platform device:

  hub6_init()
    -> platform_device_register(&hub6_device)
       -> device_initialize(&hub6_device.dev)
       -> setup_pdev_dma_masks(&hub6_device)
       -> platform_device_add(&hub6_device)

This leads to a reference leak when platform_device_register() fails.
Fix this by calling platform_device_put() before returning the error.

The issue was identified by a static analysis tool I developed and
confirmed by manual review.

Fixes: ec9f47cd6a14c ("[PATCH] Serial: Split 8250 port table")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 drivers/tty/serial/8250/8250_hub6.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_hub6.c b/drivers/tty/serial/8250/8250_hub6.c
index 273f59b9bca5..005dd6bec3da 100644
--- a/drivers/tty/serial/8250/8250_hub6.c
+++ b/drivers/tty/serial/8250/8250_hub6.c
@@ -43,9 +43,14 @@ static struct platform_device hub6_device = {
 
 static int __init hub6_init(void)
 {
-	return platform_device_register(&hub6_device);
-}
+	int ret;
+
+	ret = platform_device_register(&hub6_device);
+	if (ret)
+		platform_device_put(&hub6_device);
 
+	return ret;
+}
 module_init(hub6_init);
 
 MODULE_AUTHOR("Russell King");
-- 
2.43.0