staging: comedi: gsc_hpdi: check dma_alloc_coherent() return value

The "auto-attach" handler function `gsc_hpdi_auto_attach()` calls
`dma_alloc_coherent()` in a loop to allocate some DMA data buffers, and
also calls it to allocate a buffer for a DMA descriptor chain.  However,
it does not check the return value of any of these calls.  Change
`gsc_hpdi_auto_attach()` to return `-ENOMEM` if any of these
`dma_alloc_coherent()` calls fail.  This will result in the comedi core
calling the "detach" handler `gsc_hpdi_detach()` as part of the
clean-up, which will call `gsc_hpdi_free_dma()` to free any allocated
DMA coherent memory buffers.

Cc: <stable@vger.kernel.org> #4.6+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20191216110823.216237-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c
index 4bdf44d..dc62db1 100644 (file)
--- a/drivers/staging/comedi/drivers/gsc_hpdi.c
+++ b/drivers/staging/comedi/drivers/gsc_hpdi.c
@@ -623,6 +623,11 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev,
                    dma_alloc_coherent(&pcidev->dev, DMA_BUFFER_SIZE,
                                       &devpriv->dio_buffer_phys_addr[i],
                                       GFP_KERNEL);
+               if (!devpriv->dio_buffer[i]) {
+                       dev_warn(dev->class_dev,
+                                "failed to allocate DMA buffer\n");
+                       return -ENOMEM;
+               }
        }
        /* allocate dma descriptors */
        devpriv->dma_desc = dma_alloc_coherent(&pcidev->dev,
@@ -630,6 +635,11 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev,
                                               NUM_DMA_DESCRIPTORS,
                                               &devpriv->dma_desc_phys_addr,
                                               GFP_KERNEL);
+       if (!devpriv->dma_desc) {
+               dev_warn(dev->class_dev,
+                        "failed to allocate DMA descriptors\n");
+               return -ENOMEM;
+       }
        if (devpriv->dma_desc_phys_addr & 0xf) {
                dev_warn(dev->class_dev,
                         " dma descriptors not quad-word aligned (bug)\n");