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staging: comedi: ni_labpc: fix possible double-free of dma_buffer

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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@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott
2013-06-28 17:09:17 +01:00
committed by Greg Kroah-Hartman
parent c383e2d6da
commit 725a70d8a6
1 changed files with 6 additions and 4 deletions
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10
drivers/staging/comedi/drivers/ni_labpc.c
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@@ -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);
}
}
}