Re: [PATCH] Fix NULL dereference when suspending snd_opl3sa2

From: Takashi Iwai
Date: Tue Mar 17 2009 - 04:30:48 EST


At Mon, 16 Mar 2009 21:32:25 +0100,
Krzysztof Helt wrote:
>
> On Mon, 16 Mar 2009 15:16:08 +0100
> Lubomir Rintel <lkundrak@xxxxx> wrote:
>
> > On Mon, 2009-03-16 at 11:01 +0100, Lubomir Rintel wrote:
> > > This should fix the following OOPS:
> > > http://www.kerneloops.org/raw.php?rawid=80591&msgid=
> >
>
> > This is the same issue, with 2.6.28:
> > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=519939
> >
> >
>
> One should no force loading of the snd-opl3sa2 driver
> in the above cases. It was forced as the opl3sa2 is a PnP chip
> and the drivers were loaded as plain ISA devices.
>
> However, this is not a cause of the OOPS. The cause is that
> despite the driver returns -ENODEV, the higher layer
> hides it and the driver is bound to the bus. I suppose,
> the suspend and resume functions are called on it.
>
> Look at the ISA probe function:
>
> static int __devinit snd_opl3sa2_isa_probe(struct device *pdev,
> unsigned int dev)
> {
> struct snd_card *card;
> int err;
>
> card = snd_opl3sa2_card_new(dev);
> if (! card)
> return -ENOMEM;
> snd_card_set_dev(card, pdev);
> if ((err = snd_opl3sa2_probe(card, dev)) < 0) {
> snd_card_free(card);
> return err;
> }
> dev_set_drvdata(pdev, card);
> return 0;
> }
>
> If the probe function fails, the drvdata is
> never set to the snd_card structure pointer.
>
> The patch below should fix suspend and resume
> functions.
>
> Regards,
> Krzysztof
> PS. It is the same situation for PnP and
> BIOS PnP probing in this driver.
> ---
>
> Fix the OOPS during a opl3sa2 card suspend
> and resume if the driver is loaded but the card
> is not found.
>
> Signed-off-by: Krzysztof Helt <krzysztof.h1@xxxxx>

This patch looks good. I applied it to sound git tree now.

Thanks,

Takashi


> --- a/sound/isa/opl3sa2.c~ 2008-10-13 18:03:52.000000000 +0200
> +++ b/sound/isa/opl3sa2.c 2009-03-16 21:20:30.841348261 +0100
> @@ -550,21 +550,27 @@ static int __devinit snd_opl3sa2_mixer(s
> #ifdef CONFIG_PM
> static int snd_opl3sa2_suspend(struct snd_card *card, pm_message_t state)
> {
> - struct snd_opl3sa2 *chip = card->private_data;
> + if (card) {
> + struct snd_opl3sa2 *chip = card->private_data;
>
> - snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
> - chip->wss->suspend(chip->wss);
> - /* power down */
> - snd_opl3sa2_write(chip, OPL3SA2_PM_CTRL, OPL3SA2_PM_D3);
> + snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
> + chip->wss->suspend(chip->wss);
> + /* power down */
> + snd_opl3sa2_write(chip, OPL3SA2_PM_CTRL, OPL3SA2_PM_D3);
> + }
>
> return 0;
> }
>
> static int snd_opl3sa2_resume(struct snd_card *card)
> {
> - struct snd_opl3sa2 *chip = card->private_data;
> + struct snd_opl3sa2 *chip;
> int i;
>
> + if (!card)
> + return 0;
> +
> + chip = card->private_data;
> /* power up */
> snd_opl3sa2_write(chip, OPL3SA2_PM_CTRL, OPL3SA2_PM_D0);
>
>
> --
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