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ASoC: simple-card: Fix crash in asoc_simple_card_unref() 

If asoc_simple_card_probe() fails, asoc_simple_card_unref() may be
called before dev_set_drvdata(), causing a NULL pointer dereference in
asoc_simple_card_unref():

    Unable to handle kernel NULL pointer dereference at virtual address 000000d4
    ...
    PC is at asoc_simple_card_unref+0x14/0x48
    LR is at asoc_simple_card_probe+0x3d4/0x40c

This typically happens because asoc_simple_card_parse_of() returns
-EPROBE_DEFER, but other failure modes are possible.
devm_snd_soc_register_card()/snd_soc_register_card() may fail either
before or after dev_set_drvdata().

Pass a snd_soc_card pointer instead of a platform_device pointer to
asoc_simple_card_unref() to fix this.

Note that if CONFIG_OF_DYNAMIC=n, of_node_put() is a dummy, and gcc may
optimize away the loop over card->dai_link, never actually dereferencing
card, and thus avoiding the crash...

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: e512e001da ("ASoC: simple-card: Fix the reference count of device nodes")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Geert Uytterhoeven 2015-01-13 21:03:37 +01:00 committed by Mark Brown
parent 97bf6af1f9
commit 7ddfdb5c5a
1 changed files with 3 additions and 4 deletions
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7
sound/soc/generic/simple-card.c
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@ -452,9 +452,8 @@ static int asoc_simple_card_parse_of(struct device_node *node,
}
/* Decrease the reference count of the device nodes */
static int asoc_simple_card_unref(struct platform_device *pdev)
static int asoc_simple_card_unref(struct snd_soc_card *card)
{
struct snd_soc_card *card = platform_get_drvdata(pdev);
struct snd_soc_dai_link *dai_link;
int num_links;
@ -556,7 +555,7 @@ static int asoc_simple_card_probe(struct platform_device *pdev)
return ret;
err:
asoc_simple_card_unref(pdev);
asoc_simple_card_unref(&priv->snd_card);
return ret;
}
@ -572,7 +571,7 @@ static int asoc_simple_card_remove(struct platform_device *pdev)
snd_soc_jack_free_gpios(&simple_card_mic_jack, 1,
&simple_card_mic_jack_gpio);
return asoc_simple_card_unref(pdev);
return asoc_simple_card_unref(card);
}
static const struct of_device_id asoc_simple_of_match[] = {