@@ -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);
This is a note to let you know that I have just added a patch titled staging: comedi: das1800: fix possible NULL dereference to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 96c4a4358a2a418427f907fc81f62a0c80b1ebf4 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten <hsweeten@visionengravers.com> Date: Fri, 8 Apr 2016 10:14:58 -0700 Subject: 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> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/staging/comedi/drivers/das1800.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) -- 2.7.4