1. Patchew
  2. linux
  3. View series

[PATCH] media: vimc: fix reference leak on failed device registration

Guangshuo Li posted 1 patch 2 months ago 
drivers/media/test-drivers/vimc/vimc-core.c | 1 +
1 file changed, 1 insertion(+)
[PATCH] media: vimc: fix reference leak on failed device registration
Posted by Guangshuo Li 2 months ago 
When platform_device_register() fails in vimc_init(), the embedded
struct device in vimc_pdev has already been initialized by
device_initialize(), but the failure path returns the error without
dropping the device reference for the current platform device:

  vimc_init()
    -> platform_device_register(&vimc_pdev)
       -> device_initialize(&vimc_pdev.dev)
       -> setup_pdev_dma_masks(&vimc_pdev)
       -> platform_device_add(&vimc_pdev)

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: 4babf057c143f ("media: vimc: allocate vimc_device dynamically")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/media/test-drivers/vimc/vimc-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/test-drivers/vimc/vimc-core.c b/drivers/media/test-drivers/vimc/vimc-core.c
index 15167e127461..fee0c7a09c4f 100644
--- a/drivers/media/test-drivers/vimc/vimc-core.c
+++ b/drivers/media/test-drivers/vimc/vimc-core.c
@@ -421,6 +421,7 @@ static int __init vimc_init(void)
 	if (ret) {
 		dev_err(&vimc_pdev.dev,
 			"platform device registration failed (err=%d)\n", ret);
+		platform_device_put(&vimc_pdev);
 		return ret;
 	}
 
-- 
2.43.0
Re: [PATCH] media: vimc: fix reference leak on failed device registration
Posted by Shuah Khan 2 months ago 
On 4/15/26 09:45, Guangshuo Li wrote:
> When platform_device_register() fails in vimc_init(), the embedded
> struct device in vimc_pdev has already been initialized by
> device_initialize(), but the failure path returns the error without
> dropping the device reference for the current platform device:
> 
>    vimc_init()
>      -> platform_device_register(&vimc_pdev)
>         -> device_initialize(&vimc_pdev.dev)
>         -> setup_pdev_dma_masks(&vimc_pdev)
>         -> platform_device_add(&vimc_pdev)
> 
> 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.

Can you share your manual review?

Can other static analysis tools for example scripts/coccinelle support
your findings?

> 
> Fixes: 4babf057c143f ("media: vimc: allocate vimc_device dynamically")
> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
> ---
>   drivers/media/test-drivers/vimc/vimc-core.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/media/test-drivers/vimc/vimc-core.c b/drivers/media/test-drivers/vimc/vimc-core.c
> index 15167e127461..fee0c7a09c4f 100644
> --- a/drivers/media/test-drivers/vimc/vimc-core.c
> +++ b/drivers/media/test-drivers/vimc/vimc-core.c
> @@ -421,6 +421,7 @@ static int __init vimc_init(void)
>   	if (ret) {
>   		dev_err(&vimc_pdev.dev,
>   			"platform device registration failed (err=%d)\n", ret);
> +		platform_device_put(&vimc_pdev);

Where does platform_device_get() happen when platform_device_register() fails?

thanks,
-- Shuah
Re: [PATCH] media: vimc: fix reference leak on failed device registration
Posted by Guangshuo Li 2 months ago 
Hi Shuah,

Thanks for reviewing.

On Thu, 16 Apr 2026 at 00:01, Shuah Khan <skhan@linuxfoundation.org> wrote:
>

>
> Can you share your manual review?
>
> Can other static analysis tools for example scripts/coccinelle support
> your findings?
>
> >
> > Fixes: 4babf057c143f ("media: vimc: allocate vimc_device dynamically")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
> > ---
> >   drivers/media/test-drivers/vimc/vimc-core.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/media/test-drivers/vimc/vimc-core.c b/drivers/media/test-drivers/vimc/vimc-core.c
> > index 15167e127461..fee0c7a09c4f 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-core.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-core.c
> > @@ -421,6 +421,7 @@ static int __init vimc_init(void)
> >       if (ret) {
> >               dev_err(&vimc_pdev.dev,
> >                       "platform device registration failed (err=%d)\n", ret);
> > +             platform_device_put(&vimc_pdev);
>
> Where does platform_device_get() happen when platform_device_register() fails?
>
> thanks,
> -- Shuah

My manual review was based on the platform_device_register() call
chain and its documented lifetime rules.

The relevant code path is:

ret = platform_device_register(&vimc_pdev);
if (ret) {
dev_err(&vimc_pdev.dev,
"platform device registration failed (err=%d)\n", ret);
return ret;
}

and

int platform_device_register(struct platform_device *pdev)
{
device_initialize(&pdev->dev);
setup_pdev_dma_masks(pdev);
return platform_device_add(pdev);
}

If platform_device_add() fails, platform_device_register() returns an
error, but the reference initialized by device_initialize() is still
owned by the caller. The API documentation for platform_device_register()
also explicitly says:

"Never directly free @pdev after calling this function, even if it
returned an error! Always use platform_device_put() to give up the
reference initialised in this function instead."

So there is no matching platform_device_get() on the failure path.
The reference comes from device_initialize(), and platform_device_put()
is needed to drop that initial reference when registration fails.

That was also how I manually confirmed the issue after the tool report:
I checked the platform_device_register() / platform_device_add()
implementation and verified that the vimc failure path returns directly
without calling platform_device_put().

I found this issue using a tool I recently developed. The scan was run
on kernel version v7.0-1262-g4fa12523f7bc.

Thanks,
Guangshuo
Re: [PATCH] media: vimc: fix reference leak on failed device registration
Posted by Shuah Khan 2 months ago 
On 4/15/26 10:56, Guangshuo Li wrote:
> Hi Shuah,
> 
> Thanks for reviewing.
> 
> On Thu, 16 Apr 2026 at 00:01, Shuah Khan <skhan@linuxfoundation.org> wrote:
>>
> 
>>
>> Can you share your manual review?
>>
>> Can other static analysis tools for example scripts/coccinelle support
>> your findings?
>>

Did you try other static analysis tools in the kernel?

>>>
>>> Fixes: 4babf057c143f ("media: vimc: allocate vimc_device dynamically")
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
>>> ---
>>>    drivers/media/test-drivers/vimc/vimc-core.c | 1 +
>>>    1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/media/test-drivers/vimc/vimc-core.c b/drivers/media/test-drivers/vimc/vimc-core.c
>>> index 15167e127461..fee0c7a09c4f 100644
>>> --- a/drivers/media/test-drivers/vimc/vimc-core.c
>>> +++ b/drivers/media/test-drivers/vimc/vimc-core.c
>>> @@ -421,6 +421,7 @@ static int __init vimc_init(void)
>>>        if (ret) {
>>>                dev_err(&vimc_pdev.dev,
>>>                        "platform device registration failed (err=%d)\n", ret);
>>> +             platform_device_put(&vimc_pdev);
>>
>> Where does platform_device_get() happen when platform_device_register() fails?
>>
>> thanks,
>> -- Shuah
> 
> My manual review was based on the platform_device_register() call
> chain and its documented lifetime rules.
> 
> The relevant code path is:
> 
> ret = platform_device_register(&vimc_pdev);
> if (ret) {
> dev_err(&vimc_pdev.dev,
> "platform device registration failed (err=%d)\n", ret);
> return ret;
> }
> 
> and
> 
> int platform_device_register(struct platform_device *pdev)
> {
> device_initialize(&pdev->dev);
> setup_pdev_dma_masks(pdev);
> return platform_device_add(pdev);
> }
> 
> If platform_device_add() fails, platform_device_register() returns an
> error, but the reference initialized by device_initialize() is still
> owned by the caller. The API documentation for platform_device_register()
> also explicitly says:
> 
> "Never directly free @pdev after calling this function, even if it
> returned an error! Always use platform_device_put() to give up the
> reference initialised in this function instead."
> 
> So there is no matching platform_device_get() on the failure path.
> The reference comes from device_initialize(), and platform_device_put()
> is needed to drop that initial reference when registration fails.
> 
> That was also how I manually confirmed the issue after the tool report:
> I checked the platform_device_register() / platform_device_add()
> implementation and verified that the vimc failure path returns directly
> without calling platform_device_put().
> 
> I found this issue using a tool I recently developed. The scan was run
> on kernel version v7.0-1262-g4fa12523f7bc.

There are several calls to platform_device_register() all over the kernel.
Did your tool find all other cases or just this one?

thanks,
-- Shuah
Re: [PATCH] media: vimc: fix reference leak on failed device registration
Posted by Guangshuo Li 2 months ago 
Hi Shuah,

Thanks for reviewing.

On Thu, 16 Apr 2026 at 04:49, Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> On 4/15/26 10:56, Guangshuo Li wrote:
> > Hi Shuah,
> >
> > Thanks for reviewing.
> >
> > On Thu, 16 Apr 2026 at 00:01, Shuah Khan <skhan@linuxfoundation.org> wrote:
> >>
> >
> >>
> >> Can you share your manual review?
> >>
> >> Can other static analysis tools for example scripts/coccinelle support
> >> your findings?
> >>
>
> Did you try other static analysis tools in the kernel?
>
I have not used other static analysis tools for this case.

> There are several calls to platform_device_register() all over the kernel.
> Did your tool find all other cases or just this one?
>
> thanks,
> -- Shuah

My tool also identified other similar issues in the kernel, and I have
posted corresponding patches for them, for example:

[PATCH] eeprom: digsy_mtc: fix reference leak on failed device registration
https://patchew.org/linux/20260415165203.3584869-1-lgs201920130244@gmail.com/

[PATCH] arm_pmu: acpi: fix reference leak on failed device registration
https://patchew.org/linux/20260415174159.3625777-1-lgs201920130244@gmail.com/

Thanks,
Guangshuo

Patchew 2.1-devel-ea86937

© 2016 - 2026 Red Hat, Inc.