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ALSA: hda: hdac_stream: fix potential locking issue in snd_hdac_stream_assign()

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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>
This commit is contained in:
Pierre-Louis Bossart 2021-09-24 14:24:14 -05:00 committed by Takashi Iwai
parent 882e013a32
commit 1465d06a6d
1 changed files with 2 additions and 2 deletions
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4
sound/hda/hdac_stream.c
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@ -296,6 +296,7 @@ struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
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 @@ struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
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);