• Takashi Iwai's avatar
    ALSA: pcm : Call kill_fasync() in stream lock · 3aa02cb6
    Takashi Iwai authored
    
    
    Currently kill_fasync() is called outside the stream lock in
    snd_pcm_period_elapsed().  This is potentially racy, since the stream
    may get released even during the irq handler is running.  Although
    snd_pcm_release_substream() calls snd_pcm_drop(), this doesn't
    guarantee that the irq handler finishes, thus the kill_fasync() call
    outside the stream spin lock may be invoked after the substream is
    detached, as recently reported by KASAN.
    
    As a quick workaround, move kill_fasync() call inside the stream
    lock.  The fasync is rarely used interface, so this shouldn't have a
    big impact from the performance POV.
    
    Ideally, we should implement some sync mechanism for the proper finish
    of stream and irq handler.  But this oneliner should suffice for most
    cases, so far.
    
    Reported-by: default avatarBaozeng Ding <sploving1@gmail.com>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    3aa02cb6