diff options
| author | Takashi Iwai <tiwai@suse.de> | 2022-03-22 18:07:18 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-28 09:59:53 +0200 |
| commit | 4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5 (patch) | |
| tree | b81e03bb7dcc2840a865e6bc6e5053f7e5855538 | |
| parent | 0090c13cbbdffd7da079ac56f80373a9a1be0bf8 (diff) | |
| download | linux-stable-4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5.tar.gz linux-stable-4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5.tar.bz2 linux-stable-4d1b0ace2d56dc27cc4921eda7fae57f77f03eb5.zip | |
ALSA: pcm: Fix races among concurrent read/write and buffer changes
commit dca947d4d26dbf925a64a6cfb2ddbc035e831a3d upstream.
In the current PCM design, the read/write syscalls (as well as the
equivalent ioctls) are allowed before the PCM stream is running, that
is, at PCM PREPARED state. Meanwhile, we also allow to re-issue
hw_params and hw_free ioctl calls at the PREPARED state that may
change or free the buffers, too. The problem is that there is no
protection against those mix-ups.
This patch applies the previously introduced runtime->buffer_mutex to
the read/write operations so that the concurrent hw_params or hw_free
call can no longer interfere during the operation. The mutex is
unlocked before scheduling, so we don't take it too long.
Cc: <stable@vger.kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322170720.3529-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/core/pcm_lib.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 4f4b4739f987..27ee0a0bee04 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1906,9 +1906,11 @@ static int wait_for_avail(struct snd_pcm_substream *substream, if (avail >= runtime->twake) break; snd_pcm_stream_unlock_irq(substream); + mutex_unlock(&runtime->buffer_mutex); tout = schedule_timeout(wait_time); + mutex_lock(&runtime->buffer_mutex); snd_pcm_stream_lock_irq(substream); set_current_state(TASK_INTERRUPTIBLE); switch (runtime->status->state) { @@ -2202,6 +2204,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream, nonblock = !!(substream->f_flags & O_NONBLOCK); + mutex_lock(&runtime->buffer_mutex); snd_pcm_stream_lock_irq(substream); err = pcm_accessible_state(runtime); if (err < 0) @@ -2293,6 +2296,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream, if (xfer > 0 && err >= 0) snd_pcm_update_state(substream, runtime); snd_pcm_stream_unlock_irq(substream); + mutex_unlock(&runtime->buffer_mutex); return xfer > 0 ? (snd_pcm_sframes_t)xfer : err; } EXPORT_SYMBOL(__snd_pcm_lib_xfer); |