ASoC: rt5640: Fix NULL dereference on module unload

The rt5640->jack is NULL if jack is already disabled at the time of driver's module unloading.

---

Changelog:

v2: - Addressed review comment from Takashi Iwai by making patch's diff a
bit cleaner and simpler.

- Addressed review comment from Mark Brown by removing noisy backtrace from the commit's message and moving it after --- in order to keep it discoverable in the ML archive.

Backtrace:

 Unable to handle kernel NULL pointer dereference at virtual address 00000024
 ...
 (rt5640_set_jack [snd_soc_rt5640])
 (snd_soc_component_set_jack [snd_soc_core])
 (soc_remove_component [snd_soc_core])
 (soc_cleanup_card_resources [snd_soc_core])
 (snd_soc_unregister_card [snd_soc_core])
 (tegra_rt5640_remove [snd_soc_tegra_rt5640])
 (platform_drv_remove)
 (device_release_driver_internal)
 (driver_detach)
 (bus_remove_driver)
 (tegra_rt5640_driver_exit
 (sys_delete_module)

 sound/soc/codecs/rt5640.c | 7 +++++++
 1 file changed, 7 insertions(+)

index adbae1f36a8a..747ca248bf10 100644
@@ -2432,6 +2432,13 @@ static void rt5640_disable_jack_detect(struct snd_soc_component *component)
 {
 	struct rt5640_priv *rt5640 = snd_soc_component_get_drvdata(component);
 
+	/*
+	 * soc_remove_component() force-disables jack and thus rt5640->jack
+	 * could be NULL at the time of driver's module unloading.
+	 */
+	if (!rt5640->jack)
+		return;
+
 	disable_irq(rt5640->irq);
 	rt5640_cancel_work(rt5640);
 

2.24.0

The patch

ASoC: rt5640: Fix NULL dereference on module unload

has been applied to the asoc tree at

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.5

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying to this mail.

Thanks,
Mark

From 89b71b3f02d8ae5a08a1dd6f4a2098b7b868d498 Mon Sep 17 00:00:00 2001
From: Dmitry Osipenko <[email protected]>
Date: Mon, 6 Jan 2020 04:47:07 +0300
Subject: [PATCH] ASoC: rt5640: Fix NULL dereference on module unload

The rt5640->jack is NULL if jack is already disabled at the time of driver's module unloading.

---
 sound/soc/codecs/rt5640.c | 7 +++++++
 1 file changed, 7 insertions(+)

index adbae1f36a8a..747ca248bf10 100644
@@ -2432,6 +2432,13 @@ static void rt5640_disable_jack_detect(struct snd_soc_component *component)
 {
 	struct rt5640_priv *rt5640 = snd_soc_component_get_drvdata(component);
 
+	/*
+	 * soc_remove_component() force-disables jack and thus rt5640->jack
+	 * could be NULL at the time of driver's module unloading.
+	 */
+	if (!rt5640->jack)
+		return;
+
 	disable_irq(rt5640->irq);
 	rt5640_cancel_work(rt5640);
 

2.20.1