linux-kernel - Re: [PATCH v3] [ARM] fix reference leak in locomo_init_one

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Message-ID: <Z31kfQiLA6pddH_a@shell.armlinux.org.uk>
Date: Tue, 7 Jan 2025 17:29:33 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Ma Ke <make24@...as.ac.cn>
Cc: elder@...nel.org, sumit.garg@...aro.org, gregkh@...uxfoundation.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v3] [ARM] fix reference leak in locomo_init_one_child()

On Tue, Jan 07, 2025 at 10:07:14AM +0800, Ma Ke wrote:
> Once device_register() failed, we should call put_device() to
> decrement reference count for cleanup. Or it could cause memory leak.
> 
> device_register() includes device_add(). As comment of device_add()
> says, 'if device_add() succeeds, you should call device_del() when you
> want to get rid of it. If device_add() has not succeeded, use only
> put_device() to drop the reference count'.
> 
> Found by code review.
> 
> Cc: stable@...r.kernel.org
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
> Changes in v3:
> - modified the patch as suggestions;
> Changes in v2:
> - modified the patch as suggestions.
> ---
>  arch/arm/common/locomo.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c
> index cb6ef449b987..9e275b2105c2 100644
> --- a/arch/arm/common/locomo.c
> +++ b/arch/arm/common/locomo.c
> @@ -220,13 +220,11 @@ static int
>  locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info)
>  {
>  	struct locomo_dev *dev;
> -	int ret;
> +	int ret = 0;

The code around "ret" becomes:

	int ret = 0;

...

        ret = device_register(&dev->dev);

Nothing between these two statements references "ret", and the present
goto is eliminated in your patch.

So, why do we need to initialise ret to zero where it is declared?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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