linux-kernel - [PATCH v0] ASoC: rt5645: Fix errorenous cleanup order

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Date:   Mon, 16 May 2022 17:20:35 +0800
From:   Lin Ma <linma@....edu.cn>
To:     oder_chiou@...ltek.com, lgirdwood@...il.com, broonie@...nel.org,
        perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Cc:     Lin Ma <linma@....edu.cn>
Subject: [PATCH v0] ASoC: rt5645: Fix errorenous cleanup order

There is a logic error when removing rt5645 device as the function
rt5645_i2c_remove() first cancel the &rt5645->jack_detect_work and
delete the &rt5645->btn_check_timer latter. However, since the timer
handler rt5645_btn_check_callback() will re-queue the jack_detect_work,
this cleanup order is buggy.

That is, once the del_timer_sync in rt5645_i2c_remove is concurrently
run with the rt5645_btn_check_callback, the canceled jack_detect_work
will be rescheduled again, leading to possible use-after-free.

This patch fix the issue by placing the del_timer_sync function before
the cancel_delayed_work_sync.

Signed-off-by: Lin Ma <linma@....edu.cn>
---
 sound/soc/codecs/rt5645.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/rt5645.c b/sound/soc/codecs/rt5645.c
index 197c56047947..71a8990ba548 100644
--- a/sound/soc/codecs/rt5645.c
+++ b/sound/soc/codecs/rt5645.c
@@ -4154,9 +4154,14 @@ static int rt5645_i2c_remove(struct i2c_client *i2c)
 	if (i2c->irq)
 		free_irq(i2c->irq, rt5645);

+	/*
+	 * Since the rt5645_btn_check_callback() can queue jack_detect_work,
+	 * the timer need to be delted first
+	 */
+	del_timer_sync(&rt5645->btn_check_timer);
+
 	cancel_delayed_work_sync(&rt5645->jack_detect_work);
 	cancel_delayed_work_sync(&rt5645->rcclock_work);
-	del_timer_sync(&rt5645->btn_check_timer);

 	regulator_bulk_disable(ARRAY_SIZE(rt5645->supplies), rt5645->supplies);

-- 
2.35.1