On Fri, Apr 26, 2019 at 04:03:47PM -0500, Pierre-Louis Bossart wrote:
> On 4/26/19 11:47 AM, Ross Zwisler wrote:
> > Currently in sst_dsp_new() if we get an error return from sst_dma_new()
> > we just print an error message and then still complete the function
> > successfully. This means that we are trying to run without sst->dma
> > properly set up, which will result in NULL pointer dereference when
> > sst->dma is later used. This was happening for me in
> > sst_dsp_dma_get_channel():
> >
> > struct sst_dma *dma = dsp->dma;
> > ...
> > dma->ch = dma_request_channel(mask, dma_chan_filter, dsp);
> >
> > This resulted in:
> >
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
> > IP: sst_dsp_dma_get_channel+0x4f/0x125 [snd_soc_sst_firmware]
> >
> > Fix this by adding proper error handling for the case where we fail to
> > set up DMA.
> >
> > Signed-off-by: Ross Zwisler <zwisler@xxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> > sound/soc/intel/common/sst-firmware.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/intel/common/sst-firmware.c b/sound/soc/intel/common/sst-firmware.c
> > index 1e067504b6043..9be3a793a55e3 100644
> > --- a/sound/soc/intel/common/sst-firmware.c
> > +++ b/sound/soc/intel/common/sst-firmware.c
> > @@ -1251,11 +1251,15 @@ struct sst_dsp *sst_dsp_new(struct device *dev,
> > goto irq_err;
> > err = sst_dma_new(sst);
> > - if (err)
> > + if (err) {
> > dev_warn(dev, "sst_dma_new failed %d\n", err);
> > + goto dma_err;
> > + }
>
> Thanks for the patch.
> The fix looks correct, but does it make sense to keep a dev_warn() here?
> Should it be changed to dev_err() instead since as you mentioned it's fatal
> to keep going.
> Also you may want to mention in the commit message that this should only
> impact Broadwell and maybe the legacy Baytrail driver. IIRC we don't use the
> DMAs in other cases.
Sure, I'll address both of these in a v2. Thank you for the quick review.
