Re: sound/pci/hda/patch_ca0132.c: potential null dereference 'dma_engine'

[Takashi Iwai <tiwai@suse.de>]

At Fri, 21 Sep 2012 13:47:54 +0200,
walter harms wrote:
> 
> 
> 
> Am 21.09.2012 13:46, schrieb Takashi Iwai:
> > At Fri, 21 Sep 2012 18:22:42 +0800,
> > Fengguang Wu wrote:
> >>
> >> Hi Ian,
> >>
> >> FYI, there are new smatch warnings show up in
> >>
> >> commit 0b37d4c7982442730061a737c16939e8cc363861
> >> Author:     Ian Minett <ian_minett@creativelabs.com>
> >> Commit:     Takashi Iwai <tiwai@suse.de>
> >> CommitDate: Fri Sep 21 09:54:29 2012 +0200
> >>
> >> + sound/pci/hda/patch_ca0132.c:2056 dspxfr_image() error: potential null dereference 'dma_engine'.  (kzalloc returns null)
> >> + sound/pci/hda/patch_ca0132.c:2056 dspxfr_image() error: we previously assumed 'dma_engine' could be null (see line 1963)
> > 
> > Fixed with the patch below.  Thanks!
> > 
> > 
> > Takashi
> > 
> > => > Subject: [PATCH] ALSA: hda - Fix NULL dereference in error path of patch_ca0132.c
> > 
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> >  sound/pci/hda/patch_ca0132.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
> > index 5c6a056..03f57c9 100644
> > --- a/sound/pci/hda/patch_ca0132.c
> > +++ b/sound/pci/hda/patch_ca0132.c
> > @@ -1960,10 +1960,8 @@ static int dspxfr_image(struct hda_codec *codec,
> >  		return -EINVAL;
> >  
> >  	dma_engine = kzalloc(sizeof(*dma_engine), GFP_KERNEL);
> > -	if (!dma_engine) {
> > -		status = -ENOMEM;
> > -		goto exit;
> > -	}
> > +	if (!dma_engine)
> > +		return -ENOMEM;
> >  	memset((void *)dma_engine, 0, sizeof(*dma_engine));
> >  
> 
> Why do you need that memset() ? kzalloc() should fill the buffer with 0.

True.


Takashi