Re: [PATCH] fbdev: q40fb: fix reference leak on failed device registration

[Guangshuo Li]

Hi,

Please disregard this patch.

On Thu, 16 Apr 2026 at 03:13, Guangshuo Li <lgs201920130244@xxxxxxxxx> wrote:
>
> When platform_device_register() fails in q40fb_init(), the embedded
> struct device in q40fb_device has already been initialized by
> device_initialize(), but the failure path only unregisters the platform
> driver and does not drop the device reference for the current platform
> device:
>
>   q40fb_init()
>     -> platform_device_register(&q40fb_device)
>        -> device_initialize(&q40fb_device.dev)
>        -> setup_pdev_dma_masks(&q40fb_device)
>        -> platform_device_add(&q40fb_device)
>
> This leads to a reference leak when platform_device_register() fails.
> Fix this by calling platform_device_put() before unregistering the
> platform driver.
>
> The issue was identified by a static analysis tool I developed and
> confirmed by manual review.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
> ---
>  drivers/video/fbdev/q40fb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/q40fb.c b/drivers/video/fbdev/q40fb.c
> index 1ff8fa176124..0151a41267b3 100644
> --- a/drivers/video/fbdev/q40fb.c
> +++ b/drivers/video/fbdev/q40fb.c
> @@ -141,8 +141,10 @@ static int __init q40fb_init(void)
>
>         if (!ret) {
>                 ret = platform_device_register(&q40fb_device);
> -               if (ret)
> +               if (ret) {
> +                       platform_device_put(&q40fb_device);
>                         platform_driver_unregister(&q40fb_driver);
> +               }
>         }
>         return ret;
>  }
> --
> 2.43.0
>

After re-checking it, q40fb_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