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Message-ID: <2bd0143cf0e638c88f57409f854c0529a1b12b6b.camel@linux.intel.com>
Subject: Re: [PATCH] HID: intel-ish-hid: pci-ish:  Fix use after free bug in
  ish_remove due to race condition
From:   srinivas pandruvada <srinivas.pandruvada@linux.intel.com>
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     jikos@kernel.org, benjamin.tissoires@redhat.com, rafael@kernel.org,
        hdegoede@redhat.com, gregkh@linuxfoundation.org,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        hackerzheng666@gmail.com, 1395428693sheep@gmail.com,
        alex000young@gmail.com
Date:   Tue, 25 Apr 2023 08:55:12 -0700
In-Reply-To: <20230412171441.18958-1-zyytlz.wz@163.com>
References: <20230412171441.18958-1-zyytlz.wz@163.com>
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On Thu, 2023-04-13 at 01:14 +0800, Zheng Wang wrote:
> In ish_probe, it calls ish_dev_init to init the device. In this
> function,
> ishtp_device_init is called and &dev->bh_hbm_work is bound with 
> bh_hbm_work_fn. recv_hbm may be called to start the timer work.
> 
> If we remove the module which will call ish_remove to make cleanup,
> there may be an unfinished work. The possible sequence is as follows:
> 
> Fix it by canceling the work before cleanup in
> ishtp_bus_remove_all_clients
> 
> CPU0                  CPUc1
> 
>                     |bh_hbm_work_fn
> ish_remove      |
> ishtp_bus_remove_all_clients  |
> kfree(ishtp_dev->fw_clients); |
>                     |
>                     |&dev->fw_clients[...]
>                     |   //use
> 
> Fixes: 3703f53b99e4 ("HID: intel_ish-hid: ISH Transport layer")
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

It is a extremely rare case, so it is OK to not mark for stable.

> ---
>  drivers/hid/intel-ish-hid/ishtp/bus.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/hid/intel-ish-hid/ishtp/bus.c
> b/drivers/hid/intel-ish-hid/ishtp/bus.c
> index 81385ab37fa9..ada7cd08dbeb 100644
> --- a/drivers/hid/intel-ish-hid/ishtp/bus.c
> +++ b/drivers/hid/intel-ish-hid/ishtp/bus.c
> @@ -744,6 +744,7 @@ void ishtp_bus_remove_all_clients(struct
> ishtp_device *ishtp_dev,
>                  */
>         }
>         spin_unlock_irqrestore(&ishtp_dev->cl_list_lock, flags);
> +       cancel_work_sync(&ishtp_dev->bh_hbm_work);
>  
>         /* Release DMA buffers for client messages */
>         ishtp_cl_free_dma_buf(ishtp_dev);