[PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration

[PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration

[Guangshuo Li]

When platform_device_register() fails in digsy_mtc_eeprom_devices_init(),
the embedded struct device in digsy_mtc_eeprom has already been
initialized by device_initialize(), but the failure path only removes
the software node and does not drop the device reference for the current
platform device:

  digsy_mtc_eeprom_devices_init()
    -> platform_device_register(&digsy_mtc_eeprom)
       -> device_initialize(&digsy_mtc_eeprom.dev)
       -> setup_pdev_dma_masks(&digsy_mtc_eeprom)
       -> platform_device_add(&digsy_mtc_eeprom)

This leads to a reference leak when platform_device_register() fails.
Fix this by calling platform_device_put() after removing the software
node.

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

Fixes: c8ed97d8c3984 ("eeprom: digsy_mtc: Convert to use GPIO descriptors")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/misc/eeprom/digsy_mtc_eeprom.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/eeprom/digsy_mtc_eeprom.c b/drivers/misc/eeprom/digsy_mtc_eeprom.c
index ee58f7ce5bfa..54fcbdc0412a 100644
--- a/drivers/misc/eeprom/digsy_mtc_eeprom.c
+++ b/drivers/misc/eeprom/digsy_mtc_eeprom.c
@@ -89,8 +89,10 @@ static int __init digsy_mtc_eeprom_devices_init(void)
 		return ret;
 
 	ret = platform_device_register(&digsy_mtc_eeprom);
-	if (ret)
+	if (ret) {
 		device_remove_software_node(&digsy_mtc_eeprom.dev);
+		platform_device_put(&digsy_mtc_eeprom);
+	}
 
 	return ret;
 }
-- 
2.43.0

Re: [PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration

[Andy Shevchenko]

On Thu, Apr 16, 2026 at 12:52:02AM +0800, Guangshuo Li wrote:
> When platform_device_register() fails in digsy_mtc_eeprom_devices_init(),
> the embedded struct device in digsy_mtc_eeprom has already been
> initialized by device_initialize(), but the failure path only removes
> the software node and does not drop the device reference for the current
> platform device:
> 
>   digsy_mtc_eeprom_devices_init()
>     -> platform_device_register(&digsy_mtc_eeprom)
>        -> device_initialize(&digsy_mtc_eeprom.dev)
>        -> setup_pdev_dma_masks(&digsy_mtc_eeprom)
>        -> platform_device_add(&digsy_mtc_eeprom)
> 
> This leads to a reference leak when platform_device_register() fails.
> Fix this by calling platform_device_put() after removing the software
> node.
> 
> The issue was identified by a static analysis tool I developed and
> confirmed by manual review.

Thanks for catching this up!
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration

[Guangshuo Li]

Hi Andy, all,

Thanks for the review.

Please disregard this patch.

On Thu, 16 Apr 2026 at 15:52, Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Apr 16, 2026 at 12:52:02AM +0800, Guangshuo Li wrote:
> > When platform_device_register() fails in digsy_mtc_eeprom_devices_init(),
> > the embedded struct device in digsy_mtc_eeprom has already been
> > initialized by device_initialize(), but the failure path only removes
> > the software node and does not drop the device reference for the current
> > platform device:
> >
> >   digsy_mtc_eeprom_devices_init()
> >     -> platform_device_register(&digsy_mtc_eeprom)
> >        -> device_initialize(&digsy_mtc_eeprom.dev)
> >        -> setup_pdev_dma_masks(&digsy_mtc_eeprom)
> >        -> platform_device_add(&digsy_mtc_eeprom)
> >
> > This leads to a reference leak when platform_device_register() fails.
> > Fix this by calling platform_device_put() after removing the software
> > node.
> >
> > The issue was identified by a static analysis tool I developed and
> > confirmed by manual review.
>
> Thanks for catching this up!
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

After re-checking it, digsy_mtc_eeprom 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 confusion, and thanks again for the review.

Best regards,
Guangshuo Li

Re: [PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration

[Andy Shevchenko]

On Fri, Apr 24, 2026 at 04:21:05PM +0800, Guangshuo Li wrote:
> On Thu, 16 Apr 2026 at 15:52, Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > On Thu, Apr 16, 2026 at 12:52:02AM +0800, Guangshuo Li wrote:

...

> After re-checking it, digsy_mtc_eeprom 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.

Ah, good point! Indeed, this device is either present for the entire system
run-time or not at all. Even if it's erroneously attempted to be instantiated
it's still not a big deal.

-- 
With Best Regards,
Andy Shevchenko