ASoC: Intel: avoid Oops if DMA setup fails

commit 0efa3334d65b7f421ba12382dfa58f6ff5bf83c4 upstream.

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.

This change only affects Haswell and Broadwell systems.  Baytrail
systems explicilty opt-out of DMA via sst->pdata->resindex_dma_base
being set to -1.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Cc: stable@vger.kernel.org
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/soc/intel/common/sst-dsp.c b/sound/soc/intel/common/sst-dsp.c
index c9452e0..c0a50ec 100644 (file)
--- a/sound/soc/intel/common/sst-dsp.c
+++ b/sound/soc/intel/common/sst-dsp.c
@@ -463,11 +463,15 @@ struct sst_dsp *sst_dsp_new(struct device *dev,
                goto irq_err;
 
        err = sst_dma_new(sst);
-       if (err)
-               dev_warn(dev, "sst_dma_new failed %d\n", err);
+       if (err)  {
+               dev_err(dev, "sst_dma_new failed %d\n", err);
+               goto dma_err;
+       }
 
        return sst;
 
+dma_err:
+       free_irq(sst->irq, sst);
 irq_err:
        if (sst->ops->free)
                sst->ops->free(sst);