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

[Guangshuo Li]

Hi,

Please disregard this patch.

On Thu, 16 Apr 2026 at 02:48, Guangshuo Li <lgs201920130244@xxxxxxxxx> wrote:
>
> When platform_device_register() fails in fourport_init(), the embedded
> struct device in fourport_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:
>
>   fourport_init()
>     -> platform_device_register(&fourport_device)
>        -> device_initialize(&fourport_device.dev)
>        -> setup_pdev_dma_masks(&fourport_device)
>        -> platform_device_add(&fourport_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_fourport.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_fourport.c b/drivers/tty/serial/8250/8250_fourport.c
> index 3215b9b7afde..a65bc7316655 100644
> --- a/drivers/tty/serial/8250/8250_fourport.c
> +++ b/drivers/tty/serial/8250/8250_fourport.c
> @@ -34,7 +34,13 @@ static struct platform_device fourport_device = {
>
>  static int __init fourport_init(void)
>  {
> -       return platform_device_register(&fourport_device);
> +       int ret;
> +
> +       ret = platform_device_register(&fourport_device);
> +       if (ret)
> +               platform_device_put(&fourport_device);
> +
> +       return ret;
>  }
>
>  module_init(fourport_init);
> --
> 2.43.0
>

After re-checking it, fourport_device is a static platform_device and it
does not provide a dev.release callback. Therefore calling
platform_device_put() on the platform_device_register() failure path is
not appropriate here and can trigger the missing release callback
warning.

This falls into the same static platform_device pattern pointed out in
the other reviews, so I will drop this patch.

Sorry for the noise.

Best regards,
Guangshuo Li