Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store

[Jia-Ju Bai]

On 06/01/2017 01:33 AM, Larry Finger wrote:
> On 05/31/2017 05:29 AM, Jia-Ju Bai wrote:
> > The driver may sleep under a spin lock, and the function call path is:
> > b43legacy_attr_interfmode_store (acquire the lock by spin_lock_irqsave)
> >    b43legacy_radio_set_interference_mitigation
> >      b43legacy_radio_interference_mitigation_disable
> >        b43legacy_calc_nrssi_slope
> >          b43legacy_synth_pu_workaround
> >            might_sleep and msleep --> may sleep
> >
> > Fixing it may be complex, and a possible way is to remove
> > spin_lock_irqsave and spin_lock_irqrestore in
> > b43legacy_attr_interfmode_store, and the code has been protected by
> > mutex_lock and mutex_unlock.
> >
> > Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>
> > ---
> >   drivers/net/wireless/broadcom/b43legacy/sysfs.c |    2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/broadcom/b43legacy/sysfs.c 
> > b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> > index 2a1da15..9ede143 100644
> > --- a/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> > +++ b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
> > @@ -137,14 +137,12 @@ static ssize_t 
> > b43legacy_attr_interfmode_store(struct device *dev,
> >       }
> >         mutex_lock(&wldev->wl->mutex);
> > -    spin_lock_irqsave(&wldev->wl->irq_lock, flags);
> >         err = b43legacy_radio_set_interference_mitigation(wldev, mode);
> >       if (err)
> >           b43legacyerr(wldev->wl, "Interference Mitigation not "
> >                  "supported by device\n");
> >       mmiowb();
> > -    spin_unlock_irqrestore(&wldev->wl->irq_lock, flags);
> >       mutex_unlock(&wldev->wl->mutex);
> >         return err ? err : count;
>
> Jia-Ju,
>
> Did you actually observe the attempt to sleep under the spin lock, or 
> did you discover this using some tool? In other words, have either of 
> your patches been tested?
>
> Larry
Hi,

In fact, my reported bugs are found by a static analysis tool written by 
me, and they are checked by my review of the driver code.
I admit my patches are not well tested, and they may not well fix the bugs.
I am looking forward to opinions and suggestions :)

Thanks,
Jia-Ju Bai