Subject: [PATCH v2] arm: davinci: fix edma dmaengine induced null pointer dereference on da830

From: [email-masked] (Sekhar Nori)
Date: Tue, 12 Mar 2013 15:45:35 +0530

On 3/6/2013 10:27 PM, Tomas Novotny wrote:
> On Tue,  5 Mar 2013 10:58:22 -0500
> Matt Porter <[email-masked]> wrote:
> 
>> 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 <[email-masked]>
>> Signed-off-by: Matt Porter <[email-masked]>
>> Cc: stable at vger.kernel.org # v3.7.x+
>> ---
>> v2: Move error check out of conditional to catch all cases
>>
>>  arch/arm/mach-davinci/dma.c |    3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/arm/mach-davinci/dma.c b/arch/arm/mach-davinci/dma.c
>> index a685e97..45b7c71 100644
>> --- 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);
>>  
> 
> On the TI AM1707 based custom board:
> 
> Tested-by: Tomas Novotny <[email-masked]>

I tested it on DA830 EVM. Queuing this for v3.9-rc

Thanks,
Sekhar