ALSA: hda: hdac_stream: fix potential locking issue in snd_hdac_stream_assign()
commit 1465d06a6d8580e73ae65f8590392df58c5ed2fd upstream.
The fields 'opened', 'running', 'assigned_key' are all protected by a
spinlock, but the spinlock is not taken when looking for a
stream. This can result in a possible race between assign() and
release().
Fix by taking the spinlock before walking through the bus stream list.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210924192417.169243-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: Scott Bruce <smbruce@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index 1eb8563..9867555 100644
--- a/sound/hda/hdac_stream.c
+++ b/sound/hda/hdac_stream.c
@@ -296,6 +296,7 @@
int key = (substream->pcm->device << 16) | (substream->number << 2) |
(substream->stream + 1);
+ spin_lock_irq(&bus->reg_lock);
list_for_each_entry(azx_dev, &bus->stream_list, list) {
if (azx_dev->direction != substream->stream)
continue;
@@ -309,13 +310,12 @@
res = azx_dev;
}
if (res) {
- spin_lock_irq(&bus->reg_lock);
res->opened = 1;
res->running = 0;
res->assigned_key = key;
res->substream = substream;
- spin_unlock_irq(&bus->reg_lock);
}
+ spin_unlock_irq(&bus->reg_lock);
return res;
}
EXPORT_SYMBOL_GPL(snd_hdac_stream_assign);
