linux-kernel - [PATCH] ASoC: dapm: remove widget from dirty list on free

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Message-Id: <f8b5f031d50122bf1a9bfc9cae046badf4a7a31a.1607822410.git.tommyhebb@gmail.com>
Date:   Sat, 12 Dec 2020 17:20:12 -0800
From:   Thomas Hebb <tommyhebb@...il.com>
To:     linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>
Cc:     Thomas Hebb <tommyhebb@...il.com>, stable@...r.kernel.org,
        Jaroslav Kysela <perex@...ex.cz>,
        Liam Girdwood <lgirdwood@...il.com>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org
Subject: [PATCH] ASoC: dapm: remove widget from dirty list on free

A widget's "dirty" list_head, much like its "list" list_head, eventually
chains back to a list_head on the snd_soc_card itself. This means that
the list can stick around even after the widget (or all widgets) have
been freed. Currently, however, widgets that are in the dirty list when
freed remain there, corrupting the entire list and leading to memory
errors and undefined behavior when the list is next accessed or
modified.

I encountered this issue when a component failed to probe relatively
late in snd_soc_bind_card(), causing it to bail out and call
soc_cleanup_card_resources(), which eventually called
snd_soc_dapm_free() with widgets that were still dirty from when they'd
been added.

Fixes: db432b414e20 ("ASoC: Do DAPM power checks only for widgets changed since last run")
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Hebb <tommyhebb@...il.com>
---

 sound/soc/soc-dapm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index 7f87b449f950..148c095df27b 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -2486,6 +2486,7 @@ void snd_soc_dapm_free_widget(struct snd_soc_dapm_widget *w)
 	enum snd_soc_dapm_direction dir;

 	list_del(&w->list);
+	list_del(&w->dirty);
 	/*
 	 * remove source and sink paths associated to this widget.
 	 * While removing the path, remove reference to it from both
-- 
2.29.2