ASoC: sof_es8336: fix possible use-after-free in sof_es8336_remove()

sof_es8336_remove() calls cancel_delayed_work(). However, that
function does not wait until the work function finishes. This
means that the callback function may still be running after
the driver's remove function has finished, which would result
in a use-after-free.

Fix by calling cancel_delayed_work_sync(), which ensures that
the work is properly cancelled, no longer running, and unable
to re-schedule itself.

Fixes: 89cdb224 ("ASoC: sof_es8336: reduce pop noise on speaker")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20221205143721.3988988-1-yangyingliang@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/boards/sof_es8336.c

@@ -783,7 +783,7 @@ static int sof_es8336_remove(struct platform_device *pdev)
 	struct snd_soc_card *card = platform_get_drvdata(pdev);
 	struct sof_es8336_private *priv = snd_soc_card_get_drvdata(card);
 
-	cancel_delayed_work(&priv->pcm_pop_work);
+	cancel_delayed_work_sync(&priv->pcm_pop_work);
 	gpiod_put(priv->gpio_speakers);
 	device_remove_software_node(priv->codec_dev);
 	put_device(priv->codec_dev);