Re: [PATCH] HID: intel-ish-hid: pci-ish: Fix use after free bug in ish_remove due to race condition

[Zheng Hacker]

srinivas pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> 于2023年4月25日周二 23:55写道：
>
> 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@xxxxxxx>
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
>
> It is a extremely rare case, so it is OK to not mark for stable.

Got it, thanks!

Best regards,
Zheng

>
> > ---
> >  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);
>