linux-kernel - Re: [PATCH v2 05/12] usb: otg-fsm: Fix hrtimer list corruption

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Date:   Sat, 3 Jul 2021 19:08:09 +0800
From:   Peter Chen <peter.chen@...nel.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <treding@...dia.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sebastian Reichel <sre@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        David Heidelberg <david@...t.cz>, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v2 05/12] usb: otg-fsm: Fix hrtimer list corruption

On 21-07-02 02:43:10, Dmitry Osipenko wrote:
> The HNP work can be re-scheduled while it's still in-fly. This results in
> re-initialization of the busy work, resetting the hrtimer's list node of
> the work and crashing kernel with null dereference within kernel/timer
> once work's timer is expired. It's very easy to trigger this problem by
> re-plugging USB cable quickly. Initialize HNP work only once to fix this
> trouble.

Fully OTG compliance support has not maintained for years, what's the use case you
still want to use?

Peter
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/usb/common/usb-otg-fsm.c | 6 +++++-
>  include/linux/usb/otg-fsm.h      | 1 +
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/common/usb-otg-fsm.c b/drivers/usb/common/usb-otg-fsm.c
> index 3740cf95560e..0697fde51d00 100644
> --- a/drivers/usb/common/usb-otg-fsm.c
> +++ b/drivers/usb/common/usb-otg-fsm.c
> @@ -193,7 +193,11 @@ static void otg_start_hnp_polling(struct otg_fsm *fsm)
>  	if (!fsm->host_req_flag)
>  		return;
>  
> -	INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
> +	if (!fsm->hnp_work_inited) {
> +		INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
> +		fsm->hnp_work_inited = true;
> +	}
> +
>  	schedule_delayed_work(&fsm->hnp_polling_work,
>  					msecs_to_jiffies(T_HOST_REQ_POLL));
>  }
> diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h
> index 3aee78dda16d..784659d4dc99 100644
> --- a/include/linux/usb/otg-fsm.h
> +++ b/include/linux/usb/otg-fsm.h
> @@ -196,6 +196,7 @@ struct otg_fsm {
>  	struct mutex lock;
>  	u8 *host_req_flag;
>  	struct delayed_work hnp_polling_work;
> +	bool hnp_work_inited;
>  	bool state_changed;
>  };
>  
> -- 
> 2.30.2
> 

-- 

Thanks,
Peter Chen