[PATCH v4] [ARM] fix reference leak in locomo_init_one_child()
Alex Elder
elder at ieee.org
Wed Jan 8 19:06:16 PST 2025
On 1/7/25 9:30 PM, 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'.
And above device_register() it says:
* NOTE: _Never_ directly free @dev after calling this function, even
* if it returned an error! Always use put_device() to give up the
* reference initialized in this function instead.
> Found by code review.
>
> Cc: stable at vger.kernel.org
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Ma Ke <make24 at iscas.ac.cn>
Looks good to me. Much cleaner result.
Reviewed-by: Alex Elder <elder at kernel.org>
> ---
> Changes in v4:
> - deleted the redundant initialization;
> Changes in v3:
> - modified the patch as suggestions;
> Changes in v2:
> - modified the patch as suggestions.
> ---
> arch/arm/common/locomo.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c
> index cb6ef449b987..45106066a17f 100644
> --- a/arch/arm/common/locomo.c
> +++ b/arch/arm/common/locomo.c
> @@ -223,10 +223,8 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info)
> int ret;
>
> dev = kzalloc(sizeof(struct locomo_dev), GFP_KERNEL);
> - if (!dev) {
> - ret = -ENOMEM;
> - goto out;
> - }
> + if (!dev)
> + return -ENOMEM;
>
> /*
> * If the parent device has a DMA mask associated with it,
> @@ -254,10 +252,9 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info)
> NO_IRQ : lchip->irq_base + info->irq[0];
>
> ret = device_register(&dev->dev);
> - if (ret) {
> - out:
> - kfree(dev);
> - }
> + if (ret)
> + put_device(&dev->dev);
> +
> return ret;
> }
>
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