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

From Samuel Thibault <samuel.thibault@ens-lyon.org>
Newsgroups linux.kernel
Subject Re: A potential race in drivers/staging/speakup/speakup.ko
Date 2016-09-05 12:00 +0200
Message-ID <sdYR7-209-93@gated-at.bofh.it> (permalink)
References <sdXV0-1pk-9@gated-at.bofh.it> <sdYHo-1W2-15@gated-at.bofh.it> <sdYR6-209-61@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Pavel Andrianov, on Mon 05 Sep 2016 12:54:10 +0300, wrote:
> 05.09.2016 12:43, Samuel Thibault пишет:
> >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

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Thread

A potential race in drivers/staging/speakup/speakup.ko Pavel Andrianov <andrianov@ispras.ru> - 2016-09-05 11:00 +0200
  Re: A potential race in drivers/staging/speakup/speakup.ko Samuel Thibault <samuel.thibault@ens-lyon.org> - 2016-09-05 11:50 +0200
    Re: A potential race in drivers/staging/speakup/speakup.ko Pavel Andrianov <andrianov@ispras.ru> - 2016-09-05 12:00 +0200
      Re: A potential race in drivers/staging/speakup/speakup.ko Samuel Thibault <samuel.thibault@ens-lyon.org> - 2016-09-05 12:00 +0200
        Re: A potential race in drivers/staging/speakup/speakup.ko Pavel Andrianov <andrianov@ispras.ru> - 2016-09-05 12:40 +0200
          Re: A potential race in drivers/staging/speakup/speakup.ko Samuel Thibault <samuel.thibault@ens-lyon.org> - 2016-09-05 12:40 +0200

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