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

Luis Henriques
2013-03-19T16:25:40Z

On Mon, Mar 18, 2013 at 02:07:04PM -0700, Greg Kroah-Hartman wrote:
> 3.8-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Matt Porter <mporter@ti.com>
>
> 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@novotny.cz>
> Signed-off-by: Matt Porter <mporter@ti.com>
> Tested-by: Tomas Novotny <tomas@novotny.cz>
> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> 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);

I couldn't figure out the reason why this is tagged for v3.7.x+ only.
Shouldn't this be applied to 3.2, 3.4 and 3.5 as well?

Cheers,
--
Luis