If `labpc_attach()` allocates memory for `devpriv->dma_buffer` but fails
to request a DMA channel, it frees `devpriv->dma_buffer` but leaves the
pointer set. Later, `labpc_detach()` frees `devpriv->dma_buffer` again,
which means it has been freed twice in this case.
Fix it by only setting `devpriv->dma_buffer` in `labpc_attach()` if the
DMA channel was requested successfully.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/ni_labpc.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/comedi/drivers/ni_labpc.c b/drivers/staging/comedi/drivers/ni_labpc.c
index f161e70..0783d65 100644
--- a/drivers/staging/comedi/drivers/ni_labpc.c
+++ b/drivers/staging/comedi/drivers/ni_labpc.c
@@ -1712,13 +1712,15 @@ static int labpc_attach(struct comedi_device *dev, struct comedi_devconfig *it)
#ifdef CONFIG_ISA_DMA_API
if (dev->irq && (dma_chan == 1 || dma_chan == 3)) {
- devpriv->dma_buffer = kmalloc(dma_buffer_size,
- GFP_KERNEL | GFP_DMA);
- if (devpriv->dma_buffer) {
+ void *dma_buffer = kmalloc(dma_buffer_size,
+ GFP_KERNEL | GFP_DMA);
+
+ if (dma_buffer) {
ret = request_dma(dma_chan, dev->board_name);
if (ret == 0) {
unsigned long dma_flags;
+ devpriv->dma_buffer = dma_buffer;
devpriv->dma_chan = dma_chan;
devpriv->dma_addr =
virt_to_bus(devpriv->dma_buffer);
@@ -1728,7 +1730,7 @@ static int labpc_attach(struct comedi_device *dev, struct comedi_devconfig *it)
set_dma_mode(devpriv->dma_chan, DMA_MODE_READ);
release_dma_lock(dma_flags);
} else {
- kfree(devpriv->dma_buffer);
+ kfree(dma_buffer);
}
}
}
--
1.8.2.1
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