[alsa-devel] [patch] ALSA: echoaudio: use after free on error

[Takashi Iwai]

At Wed, 05 Mar 2014 12:21:29 +0100,
walter harms wrote:
> 
> 
> 
> Am 05.03.2014 12:07, schrieb Dan Carpenter:
> > There are some places where we dereference "chip" in the error message
> > but we've already freed it.
> > 
> > Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> > 
> > diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
> > index 166ec0c120d4..9f10c9e0df5e 100644
> > --- a/sound/pci/echoaudio/echoaudio.c
> > +++ b/sound/pci/echoaudio/echoaudio.c
> > @@ -1990,8 +1990,8 @@ static int snd_echo_create(struct snd_card *card,
> >  
> >  	if ((chip->iores = request_mem_region(chip->dsp_registers_phys, sz,
> >  					      ECHOCARD_NAME)) == NULL) {
> 
> 
> this should read:
> chip->iores = request_mem_region(chip->dsp_registers_phys, sz,ECHOCARD_NAME);
> if (chip->iores == NULL) {

In general, better not to do many things at once.
A fix patch should fix the bug, and that's all.
A coding style cleanup can be done later, if any.


Takashi

> 
> re,
>  wh
> 
> > -		snd_echo_free(chip);
> >  		dev_err(chip->card->dev, "cannot get memory region\n");
> > +		snd_echo_free(chip);
> >  		return -EBUSY;
> >  	}
> >  	chip->dsp_registers = (volatile u32 __iomem *)
> > @@ -1999,8 +1999,8 @@ static int snd_echo_create(struct snd_card *card,
> >  
> >  	if (request_irq(pci->irq, snd_echo_interrupt, IRQF_SHARED,
> >  			KBUILD_MODNAME, chip)) {
> > -		snd_echo_free(chip);
> >  		dev_err(chip->card->dev, "cannot grab irq\n");
> > +		snd_echo_free(chip);
> >  		return -EBUSY;
> >  	}
> >  	chip->irq = pci->irq;
> > @@ -2012,8 +2012,8 @@ static int snd_echo_create(struct snd_card *card,
> >  	if (snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, snd_dma_pci_data(chip->pci),
> >  				sizeof(struct comm_page),
> >  				&chip->commpage_dma_buf) < 0) {
> > -		snd_echo_free(chip);
> >  		dev_err(chip->card->dev, "cannot allocate the comm page\n");
> > +		snd_echo_free(chip);
> >  		return -ENOMEM;
> >  	}
> >  	chip->comm_page_phys = chip->commpage_dma_buf.addr;
> > @@ -2291,8 +2291,8 @@ static int snd_echo_resume(struct device *dev)
> >  
> >  	if (request_irq(pci->irq, snd_echo_interrupt, IRQF_SHARED,
> >  			KBUILD_MODNAME, chip)) {
> > -		snd_echo_free(chip);
> >  		dev_err(chip->card->dev, "cannot grab irq\n");
> > +		snd_echo_free(chip);
> >  		return -EBUSY;
> >  	}
> >  	chip->irq = pci->irq;
> > --
> > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> > the body of a message to majordomo at vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
>