linux-kernel - Re: [BUG] Kernel crash on Allwinner H3 due to sound core changes

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Date:   Thu, 8 Mar 2018 23:49:18 +0000
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Jernej Škrabec <jernej.skrabec@...l.net>,
        maxime.ripard@...e-electrons.com, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org
Subject: Re: [BUG] Kernel crash on Allwinner H3 due to sound core changes


Hi Mark,Jernej

> > Ahh.. indeed. Good catch !
> > How about to add such flag ?
> > This is just idea. No tested, No compiled, but can help you ?
> 
> I think this makes sense as a patch.  We might want to disallow
> allocating components as part of a bigger struct so everything is more
> consistent but that's a bigger thing.
(snip)
> I tested this patch and there is no crash anymore. If you will send it as a 
> fix, you can add:
> 
> Reported-by: Jernej Skrabec <jernej.skrabec@...l.net>
> Tested-by: Jernej Skrabec <jernej.skrabec@...l.net>

previous my patch used new flag (= .alloced_component),
but I think it is not good idea.
And I noticed that snd_soc_add_component() is
also calling kfree(component) (= has same bug).

So how about below one ?
I want to post it instead of previous.

# I will go to ELC next week, thus posting patch will be
# 2weeks later

------------
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index c0edac8..4a8de23 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3476,7 +3476,6 @@ int snd_soc_add_component(struct device *dev,
 err_cleanup:
 	snd_soc_component_cleanup(component);
 err_free:
-	kfree(component);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(snd_soc_add_component);
@@ -3488,7 +3487,7 @@ int snd_soc_register_component(struct device *dev,
 {
 	struct snd_soc_component *component;
 
-	component = kzalloc(sizeof(*component), GFP_KERNEL);
+	component = devm_kzalloc(dev, sizeof(*component), GFP_KERNEL);
 	if (!component)
 		return -ENOMEM;
 
@@ -3523,7 +3522,6 @@ static int __snd_soc_unregister_component(struct device *dev)
 
 	if (found) {
 		snd_soc_component_cleanup(component);
-		kfree(component);
 	}
 
 	return found;
------------