Unverified Commit 70fc5373 authored Jun 04, 2019 by Tzung-Bi Shih Committed by Mark Brown Jun 06, 2019

ASoC: core: move DAI pre-links initiation to snd_soc_instantiate_card



Kernel crashes when an ASoC component rebinding.

The dai_link->platforms has been reset to NULL by soc_cleanup_platform()
in soc_cleanup_card_resources() when un-registering component.  However,
it has no chance to re-allocate the dai_link->platforms when registering
the component again.

Move the DAI pre-links initiation from snd_soc_register_card() to
snd_soc_instantiate_card() to make sure all DAI pre-links get initiated
when component rebinding.

As an example, by using the following commands:
- echo -n max98357a > /sys/bus/platform/drivers/max98357a/unbind
- echo -n max98357a > /sys/bus/platform/drivers/max98357a/bind

Got the error message:
"Unable to handle kernel NULL pointer dereference at virtual address".

The call trace:
snd_soc_is_matching_component+0x30/0x6c
soc_bind_dai_link+0x16c/0x240
snd_soc_bind_card+0x1e4/0xb10
snd_soc_add_component+0x270/0x300
snd_soc_register_component+0x54/0x6c

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

parent 9bbc7993

sound/soc/soc-core.c

+10 −17

Original line number	Diff line number	Diff line
		@@ -2072,6 +2072,16 @@ static int snd_soc_instantiate_card(struct snd_soc_card *card)
		int ret, i, order;

		mutex_lock(&client_mutex);
		for_each_card_prelinks(card, i, dai_link) {
		ret = soc_init_dai_link(card, dai_link);
		if (ret) {
		soc_cleanup_platform(card);
		dev_err(card->dev, "ASoC: failed to init link %s: %d\n",
		dai_link->name, ret);
		mutex_unlock(&client_mutex);
		return ret;
		}
		}
		mutex_lock_nested(&card->mutex, SND_SOC_CARD_CLASS_INIT);

		card->dapm.bias_level = SND_SOC_BIAS_OFF;
		@@ -2796,26 +2806,9 @@ static int snd_soc_bind_card(struct snd_soc_card *card)
		*/
		int snd_soc_register_card(struct snd_soc_card *card)
		{
		int i, ret;
		struct snd_soc_dai_link *link;

		if (!card->name \|\| !card->dev)
		return -EINVAL;

		mutex_lock(&client_mutex);
		for_each_card_prelinks(card, i, link) {

		ret = soc_init_dai_link(card, link);
		if (ret) {
		soc_cleanup_platform(card);
		dev_err(card->dev, "ASoC: failed to init link %s\n",
		link->name);
		mutex_unlock(&client_mutex);
		return ret;
		}
		}
		mutex_unlock(&client_mutex);

		dev_set_drvdata(card->dev, card);

		snd_soc_initialize_card_lists(card);

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