lkml.org 
[lkml]   [2019]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.19 12/25] ALSA: pcm: Fix stream lock usage in snd_pcm_period_elapsed()
    Date
    From: paulhsia <paulhsia@chromium.org>

    [ Upstream commit f5cdc9d4003a2f66ea57b3edd3e04acc2b1a4439 ]

    If the nullity check for `substream->runtime` is outside of the lock
    region, it is possible to have a null runtime in the critical section
    if snd_pcm_detach_substream is called right before the lock.

    Signed-off-by: paulhsia <paulhsia@chromium.org>
    Link: https://lore.kernel.org/r/20191112171715.128727-2-paulhsia@chromium.org
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    sound/core/pcm_lib.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
    index 4e6110d778bd2..ad52126d3d22e 100644
    --- a/sound/core/pcm_lib.c
    +++ b/sound/core/pcm_lib.c
    @@ -1797,11 +1797,14 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
    struct snd_pcm_runtime *runtime;
    unsigned long flags;

    - if (PCM_RUNTIME_CHECK(substream))
    + if (snd_BUG_ON(!substream))
    return;
    - runtime = substream->runtime;

    snd_pcm_stream_lock_irqsave(substream, flags);
    + if (PCM_RUNTIME_CHECK(substream))
    + goto _unlock;
    + runtime = substream->runtime;
    +
    if (!snd_pcm_running(substream) ||
    snd_pcm_update_hw_ptr0(substream, 1) < 0)
    goto _end;
    @@ -1812,6 +1815,7 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
    #endif
    _end:
    kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
    + _unlock:
    snd_pcm_stream_unlock_irqrestore(substream, flags);
    }
    EXPORT_SYMBOL(snd_pcm_period_elapsed);
    --
    2.20.1
    \
     
     \ /
      Last update: 2019-11-22 20:55    [W:4.108 / U:0.400 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site