Hi Morimoto-san,
Thank you for the patch.
On Thursday 10 Aug 2017 02:09:21 Kuninori Morimoto wrote:
> Anton Volkov noticed that engine->dev is NULL before
> of_dma_controller_register() in probe.
> Thus there might be a NULL pointer dereference in
> rcar_dmac_chan_start_xfer while accessing chan->chan.device->dev which
> is equal to (&dmac->engine)->dev.
> To be more safety code, this patch initialize dmac->engine before it.
>
> Reported-by: Anton Volkov <avolkov@xxxxxxxxx>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> ---
>
> > Anton, Laurent
>
> I created this patch because noone posted it yesterday.
> Anton, you can use this patch and replace Author to you if you want.
> Thus, I used [RFC] on this patch
I don't think you have, the subject line is still "Re: Possible null pointer
dereference in rcar-dmac.ko" :-)
> drivers/dma/sh/rcar-dmac.c | 51 ++++++++++++++++++++-----------------------
> 1 file changed, 26 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index ffcadca..6d60628 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1818,8 +1818,32 @@ static int rcar_dmac_probe(struct platform_device
> *pdev) goto error;
> }
>
> - /* Initialize the channels. */
> - INIT_LIST_HEAD(&dmac->engine.channels);
> + /* Initialize engine */
> + engine = &dmac->engine;
> +
> + dma_cap_set(DMA_MEMCPY, engine->cap_mask);
> + dma_cap_set(DMA_SLAVE, engine->cap_mask);
> +
> + engine->dev = &pdev->dev;
> + engine->copy_align = ilog2(RCAR_DMAC_MEMCPY_XFER_SIZE);
> +
> + engine->src_addr_widths = widths;
> + engine->dst_addr_widths = widths;
> + engine->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
> + engine->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> +
> + engine->device_alloc_chan_resources =
rcar_dmac_alloc_chan_resources;
> + engine->device_free_chan_resources =
rcar_dmac_free_chan_resources;
> + engine->device_prep_dma_memcpy = rcar_dmac_prep_dma_memcpy;
> + engine->device_prep_slave_sg = rcar_dmac_prep_slave_sg;
> + engine->device_prep_dma_cyclic = rcar_dmac_prep_dma_cyclic;
> + engine->device_config = rcar_dmac_device_config;
> + engine->device_terminate_all =
rcar_dmac_chan_terminate_all;
> + engine->device_tx_status = rcar_dmac_tx_status;
> + engine->device_issue_pending = rcar_dmac_issue_pending;
> + engine->device_synchronize =
rcar_dmac_device_synchronize;
> +
> + INIT_LIST_HEAD(&engine->channels);
I don't think this fully fixes the problem, as the rcar_dmac_isr_error() IRQ
handler is still registered before all this. Furthermore, at least some of the
initialization at the end of rcar_dmac_chan_probe() has to be moved before the
rcar_dmac_isr_channel() IRQ handler registration.
Let's not commit a quick hack but fix the problem correctly, we should ensure
that all the initialization needed by IRQ handlers is performed before they
get registered.
> for (i = 0; i < dmac->n_channels; ++i) {
> ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i],
> @@ -1839,29 +1863,6 @@ static int rcar_dmac_probe(struct platform_device
> *pdev) *
> * Default transfer size of 32 bytes requires 32-byte alignment.
> */
> - engine = &dmac->engine;
> - dma_cap_set(DMA_MEMCPY, engine->cap_mask);
> - dma_cap_set(DMA_SLAVE, engine->cap_mask);
> -
> - engine->dev = &pdev->dev;
> - engine->copy_align = ilog2(RCAR_DMAC_MEMCPY_XFER_SIZE);
> -
> - engine->src_addr_widths = widths;
> - engine->dst_addr_widths = widths;
> - engine->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
> - engine->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> -
> - engine->device_alloc_chan_resources = rcar_dmac_alloc_chan_resources;
> - engine->device_free_chan_resources = rcar_dmac_free_chan_resources;
> - engine->device_prep_dma_memcpy = rcar_dmac_prep_dma_memcpy;
> - engine->device_prep_slave_sg = rcar_dmac_prep_slave_sg;
> - engine->device_prep_dma_cyclic = rcar_dmac_prep_dma_cyclic;
> - engine->device_config = rcar_dmac_device_config;
> - engine->device_terminate_all = rcar_dmac_chan_terminate_all;
> - engine->device_tx_status = rcar_dmac_tx_status;
> - engine->device_issue_pending = rcar_dmac_issue_pending;
> - engine->device_synchronize = rcar_dmac_device_synchronize;
> -
> ret = dma_async_device_register(engine);
> if (ret < 0)
> goto error;
--
Regards,
Laurent Pinchart
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