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    Subject[PATCH AUTOSEL 5.1 31/51] ASoC: core: move DAI pre-links initiation to snd_soc_instantiate_card
    Date
    From: Tzung-Bi Shih <tzungbi@google.com>

    [ Upstream commit 70fc53734e71ce51f46dfcfd1a1c319e1cfe080c ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    sound/soc/soc-core.c | 27 ++++++++++-----------------
    1 file changed, 10 insertions(+), 17 deletions(-)

    diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
    index a4668a788ed5..9df3bdeb5c47 100644
    --- a/sound/soc/soc-core.c
    +++ b/sound/soc/soc-core.c
    @@ -2069,6 +2069,16 @@ 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;
    @@ -2793,26 +2803,9 @@ 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);
    --
    2.20.1
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