Re: A potential race in drivers/staging/speakup/speakup.ko

[Pavel Andrianov]

05.09.2016 12:56, Samuel Thibault ÐÐÑÐÑ:
> Pavel Andrianov, on Mon 05 Sep 2016 12:54:10 +0300, wrote:
> > 05.09.2016 12:43, Samuel Thibault ÐÐÑÐÑ:
> > > Pavel Andrianov, on Mon 05 Sep 2016 11:51:50 +0300, wrote:
> > > > There is a potential race in drivers/staging/speakup/speakup.ko.
> > > > All operations with global pointers buff_in and buff_out are performed
> > > > without any locks. Thus, a simultaneous write (via synth_buffer_clear or
> > > > synth_buffer_add) to the pointers may lead to inconsistent data.
> > > >
> > > > Should a local lock be used here?
> > >
> > > AIUI, all callers of these functions have speakup_info.spinlock held.
> >
> > Regard a call stack
> >
> > -> synth_direct_store
> >   -> synth_printf
> >     -> synth_buffer_add
> >
> > The functions have not held speakup_info.spinlock.
>
> Apparently there is currently no caller of synth_direct_store and
> synth_store. But taking the lock here would be needed indeed.
>
> Samuel

synth_direct_store may be called via device_attributes interface. In 
which function the lock should be added?

--
Pavel Andrianov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: andrianov@xxxxxxxxx