ASoC: core: move DAI pre-links initiation to snd_soc_instantiate_card
authorTzung-Bi Shih <tzungbi@google.com>
Tue, 4 Jun 2019 03:31:02 +0000 (11:31 +0800)
committerMark Brown <broonie@kernel.org>
Thu, 6 Jun 2019 16:24:49 +0000 (17:24 +0100)
commit70fc53734e71ce51f46dfcfd1a1c319e1cfe080c
tree53eb9aece6ae4be5ade00e290d3c2ec6661d23bc
parent9bbc799318a34061703f2a980e2b6df7fc6760f0
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>
sound/soc/soc-core.c