Commit c78af348836a8d91fddc033ae68bee5dc76241c7

Authored by Geert Uytterhoeven
Committed by Greg Kroah-Hartman
1 parent 971784f012

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

commit 7ddfdb5c5a5b51bdd2cb749d8341d763b079d520 upstream.

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: e512e001dafa54e5 ("ASoC: simple-card: Fix the reference count of device nodes")
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 3 additions and 4 deletions Side-by-side Diff

sound/soc/generic/simple-card.c
... ... @@ -453,9 +453,8 @@
453 453 }
454 454  
455 455 /* Decrease the reference count of the device nodes */
456   -static int asoc_simple_card_unref(struct platform_device *pdev)
  456 +static int asoc_simple_card_unref(struct snd_soc_card *card)
457 457 {
458   - struct snd_soc_card *card = platform_get_drvdata(pdev);
459 458 struct snd_soc_dai_link *dai_link;
460 459 struct device_node *np;
461 460 int num_links;
... ... @@ -562,7 +561,7 @@
562 561 return ret;
563 562  
564 563 err:
565   - asoc_simple_card_unref(pdev);
  564 + asoc_simple_card_unref(&priv->snd_card);
566 565 return ret;
567 566 }
568 567  
... ... @@ -578,7 +577,7 @@
578 577 snd_soc_jack_free_gpios(&simple_card_mic_jack, 1,
579 578 &simple_card_mic_jack_gpio);
580 579  
581   - return asoc_simple_card_unref(pdev);
  580 + return asoc_simple_card_unref(card);
582 581 }
583 582  
584 583 static const struct of_device_id asoc_simple_of_match[] = {