[ 41/75] ARM: davinci: edma: fix dmaengine induced null pointer dereference on da830

[Greg Kroah-Hartman]

3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Porter <mporter@xxxxxx>

commit 069552777a121eb39da29de4bc0383483dbe1f7e upstream.

This adds additional error checking to the private edma api implementation
to catch the case where the edma_alloc_slot() has an invalid controller
parameter. The edma dmaengine wrapper driver relies on this condition
being handled in order to avoid setting up a second edma dmaengine
instance on DA830.

Verfied using a DA850 with the second EDMA controller platform instance
removed to simulate a DA830 which only has a single EDMA controller.

Reported-by: Tomas Novotny <tomas@xxxxxxxxxx>
Signed-off-by: Matt Porter <mporter@xxxxxx>
Tested-by: Tomas Novotny <tomas@xxxxxxxxxx>
Signed-off-by: Sekhar Nori <nsekhar@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/arm/mach-davinci/dma.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/arm/mach-davinci/dma.c
+++ b/arch/arm/mach-davinci/dma.c
@@ -743,6 +743,9 @@ EXPORT_SYMBOL(edma_free_channel);
  */
 int edma_alloc_slot(unsigned ctlr, int slot)
 {
+	if (!edma_cc[ctlr])
+		return -EINVAL;
+
 	if (slot >= 0)
 		slot = EDMA_CHAN_SLOT(slot);
 


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