diff options
| author | H Hartley Sweeten <hsweeten@visionengravers.com> | 2016-04-08 10:14:58 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-06-01 12:17:01 -0700 |
| commit | 90566b26b924c0679401ca23dbd0a1785156c488 (patch) | |
| tree | d6bb170938689090c9d90719cf89952eb1ec9f17 | |
| parent | 0b5eec3abd40b3df725dc03a5e2aad77a1f71091 (diff) | |
| download | linux-stable-90566b26b924c0679401ca23dbd0a1785156c488.tar.gz linux-stable-90566b26b924c0679401ca23dbd0a1785156c488.tar.bz2 linux-stable-90566b26b924c0679401ca23dbd0a1785156c488.zip | |
staging: comedi: das1800: fix possible NULL dereference
commit d375278d666760e195693b57415ba0a125cadd55 upstream.
DMA is optional with this driver. If it was not enabled the devpriv->dma
pointer will be NULL.
Fix the possible NULL pointer dereference when trying to disable the DMA
channels in das1800_ai_cancel() and tidy up the comments to fix the
checkpatch.pl issues:
WARNING: line over 80 characters
It's probably harmless in das1800_ai_setup_dma() because the 'desc' pointer
will not be used if DMA is disabled but fix it there also.
Fixes: 99dfc3357e98 ("staging: comedi: das1800: remove depends on ISA_DMA_API limitation")
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/comedi/drivers/das1800.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c index 940781183fac..3be10963f98b 100644 --- a/drivers/staging/comedi/drivers/das1800.c +++ b/drivers/staging/comedi/drivers/das1800.c @@ -567,14 +567,17 @@ static int das1800_cancel(struct comedi_device *dev, struct comedi_subdevice *s) struct comedi_isadma_desc *desc; int i; - outb(0x0, dev->iobase + DAS1800_STATUS); /* disable conversions */ - outb(0x0, dev->iobase + DAS1800_CONTROL_B); /* disable interrupts and dma */ - outb(0x0, dev->iobase + DAS1800_CONTROL_A); /* disable and clear fifo and stop triggering */ - - for (i = 0; i < 2; i++) { - desc = &dma->desc[i]; - if (desc->chan) - comedi_isadma_disable(desc->chan); + /* disable and stop conversions */ + outb(0x0, dev->iobase + DAS1800_STATUS); + outb(0x0, dev->iobase + DAS1800_CONTROL_B); + outb(0x0, dev->iobase + DAS1800_CONTROL_A); + + if (dma) { + for (i = 0; i < 2; i++) { + desc = &dma->desc[i]; + if (desc->chan) + comedi_isadma_disable(desc->chan); + } } return 0; @@ -934,13 +937,14 @@ static void das1800_ai_setup_dma(struct comedi_device *dev, { struct das1800_private *devpriv = dev->private; struct comedi_isadma *dma = devpriv->dma; - struct comedi_isadma_desc *desc = &dma->desc[0]; + struct comedi_isadma_desc *desc; unsigned int bytes; if ((devpriv->irq_dma_bits & DMA_ENABLED) == 0) return; dma->cur_dma = 0; + desc = &dma->desc[0]; /* determine a dma transfer size to fill buffer in 0.3 sec */ bytes = das1800_ai_transfer_size(dev, s, desc->maxsize, 300000000); |