linux-kernel - [PATCH v2] ASoC: dapm: delete dapm_kcontrol

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Date:   Mon,  4 Jun 2018 12:13:26 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     broonie@...nel.org, alsa-devel@...a-project.org
Cc:     linux-arm-msm@...r.kernel.org, lgirdwood@...il.com,
        bgoswami@...eaurora.org, tiwai@...e.com, perex@...ex.cz,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        rohkumar@....qualcomm.com,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH v2] ASoC: dapm: delete dapm_kcontrol_data paths list before freeing it

dapm_kcontrol_data is freed as part of dapm_kcontrol_free(), leaving the
paths pointer dangling in the list.

This leads to system crash when we try to unload and reload sound card.
I hit this bug during ADSP crash/reboot test case on Dragon board DB410c.

Without this patch, on SLAB Poisoning enabled build, kernel crashes with
"BUG kmalloc-128 (Tainted: G        W        ): Poison overwritten"

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
Changes since v1:
	-remove unnecessary very long bug trace.

 sound/soc/soc-dapm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index 1e9a36389667..36a39ba30226 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -433,6 +433,8 @@ static int dapm_kcontrol_data_alloc(struct snd_soc_dapm_widget *widget,
 static void dapm_kcontrol_free(struct snd_kcontrol *kctl)
 {
 	struct dapm_kcontrol_data *data = snd_kcontrol_chip(kctl);
+
+	list_del(&data->paths);
 	kfree(data->wlist);
 	kfree(data);
 }
-- 
2.16.2