linux-kernel - Re: [PATCH] power: supply: da9150: Fix use after free bug in da9150_charger

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Date:   Fri, 10 Mar 2023 00:39:13 +0100
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Zheng Wang <zyytlz.wz@....com>
Cc:     support.opensource@...semi.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, hackerzheng666@...il.com,
        1395428693sheep@...il.com, alex000young@...il.com
Subject: Re: [PATCH] power: supply: da9150: Fix use after free bug in
 da9150_charger_remove due to race condition

Hi,

On Fri, Mar 10, 2023 at 02:10:36AM +0800, Zheng Wang wrote:
> In da9150_charger_probe, &charger->otg_work is bound with
> da9150_charger_otg_work. da9150_charger_otg_ncb may be
> called to start the work.
> 
> If we remove the module which will call da9150_charger_remove
>  to make cleanup, there may be a unfinished work. The possible
>   sequence is as follows:
> 
> Fix it by canceling the work before cleanup in the mtk_jpeg_remove

mtk_jpeg_remove?

> 
> CPU0                  CPUc1
> 
>                     |da9150_charger_otg_work
> da9150_charger_remove      |
> power_supply_unregister  |
> device_unregister   |
> power_supply_dev_release|
> kfree(psy)          |
>                     |
>                     | 	power_supply_changed(charger->usb);
>                     |   //use
> Fixes: c1a281e34dae ("power: Add support for DA9150 Charger")
> Signed-off-by: Zheng Wang <zyytlz.wz@....com>
> ---

Looks correct to me, but the cancel_work_sync should happen after
usb_unregister_notifier(), otherwise there is still a race
condition.

-- Sebastian

>  drivers/power/supply/da9150-charger.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/power/supply/da9150-charger.c b/drivers/power/supply/da9150-charger.c
> index 14da5c595dd9..41b68f2f6ed8 100644
> --- a/drivers/power/supply/da9150-charger.c
> +++ b/drivers/power/supply/da9150-charger.c
> @@ -642,6 +642,7 @@ static int da9150_charger_remove(struct platform_device *pdev)
>  	struct da9150_charger *charger = platform_get_drvdata(pdev);
>  	int irq;
>  
> +	cancel_work_sync(&charger->otg_work);
>  	/* Make sure IRQs are released before unregistering power supplies */
>  	irq = platform_get_irq_byname(pdev, "CHG_VBUS");
>  	free_irq(irq, charger);
> -- 
> 2.25.1
> 

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