rtc: Fix error handling in devm_rtc_allocate_device

[PATCH] rtc: Fix error handling in devm_rtc_allocate_device

Posted by Ma Ke 1 month, 1 week ago

In rtc_allocate_device(), device_initialize() sets the reference count
to 1. In rtc_allocate_device(), when devm_add_action_or_reset() or
dev_set_name() fails after successful device initialization via
device_initialize(), rtc_allocate_device() returns an error without
properly calling put_device() and releasing the reference count.

Add proper error handling that calls put_device() in all error paths
after device_initialize(), ensuring proper resource cleanup.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 3068a254d551 ("rtc: introduce new registration method")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
 drivers/rtc/class.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index b1a2be1f9e3b..db5f33a22b14 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -379,13 +379,17 @@ struct rtc_device *devm_rtc_allocate_device(struct device *dev)
 	rtc->dev.parent = dev;
 	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
 	if (err)
-		return ERR_PTR(err);
+		goto err_put_device;
 
 	err = dev_set_name(&rtc->dev, "rtc%d", id);
 	if (err)
-		return ERR_PTR(err);
+		goto err_put_device;
 
 	return rtc;
+
+err_put_device:
+	put_device(&rtc->dev);
+	return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
 
-- 
2.17.1

Re: [PATCH] rtc: Fix error handling in devm_rtc_allocate_device

Posted by Christophe JAILLET 1 month, 1 week ago

Le 09/11/2025 à 07:08, Ma Ke a écrit :
> In rtc_allocate_device(), device_initialize() sets the reference count
> to 1. In rtc_allocate_device(), when devm_add_action_or_reset() or
> dev_set_name() fails after successful device initialization via
> device_initialize(), rtc_allocate_device() returns an error without
> properly calling put_device() and releasing the reference count.

The correct error handling is already in place and your patch looks wrong.

> Add proper error handling that calls put_device() in all error paths
> after device_initialize(), ensuring proper resource cleanup.

This is precisely the purpose of devm_add_action_or_reset().
Look at it and at the devm_rtc_release_device() which does what you expect.

CJ

> 
> Found by code review.
> 
> Cc: stable@vger.kernel.org
> Fixes: 3068a254d551 ("rtc: introduce new registration method")
> Signed-off-by: Ma Ke <make24@iscas.ac.cn>
> ---
>   drivers/rtc/class.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
> index b1a2be1f9e3b..db5f33a22b14 100644
> --- a/drivers/rtc/class.c
> +++ b/drivers/rtc/class.c
> @@ -379,13 +379,17 @@ struct rtc_device *devm_rtc_allocate_device(struct device *dev)
>   	rtc->dev.parent = dev;
>   	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
>   	if (err)
> -		return ERR_PTR(err);
> +		goto err_put_device;
>   
>   	err = dev_set_name(&rtc->dev, "rtc%d", id);
>   	if (err)
> -		return ERR_PTR(err);
> +		goto err_put_device;
>   
>   	return rtc;
> +
> +err_put_device:
> +	put_device(&rtc->dev);
> +	return ERR_PTR(err);
>   }
>   EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
>