| From 2c8f716b692867d46ce251fa55005c3882575a76 Mon Sep 17 00:00:00 2001 |
| From: Geert Uytterhoeven <geert+renesas@glider.be> |
| Date: Mon, 24 Jun 2019 14:38:18 +0200 |
| Subject: dmaengine: rcar-dmac: Reject zero-length slave DMA requests |
| |
| [ Upstream commit 78efb76ab4dfb8f74f290ae743f34162cd627f19 ] |
| |
| While the .device_prep_slave_sg() callback rejects empty scatterlists, |
| it still accepts single-entry scatterlists with a zero-length segment. |
| These may happen if a driver calls dmaengine_prep_slave_single() with a |
| zero len parameter. The corresponding DMA request will never complete, |
| leading to messages like: |
| |
| rcar-dmac e7300000.dma-controller: Channel Address Error happen |
| |
| and DMA timeouts. |
| |
| Although requesting a zero-length DMA request is a driver bug, rejecting |
| it early eases debugging. Note that the .device_prep_dma_memcpy() |
| callback already rejects requests to copy zero bytes. |
| |
| Reported-by: Eugeniu Rosca <erosca@de.adit-jv.com> |
| Analyzed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> |
| Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> |
| Signed-off-by: Vinod Koul <vkoul@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/dma/sh/rcar-dmac.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c |
| index f37a6ef4f5441..e4fe24be3d7a4 100644 |
| --- a/drivers/dma/sh/rcar-dmac.c |
| +++ b/drivers/dma/sh/rcar-dmac.c |
| @@ -1111,7 +1111,7 @@ rcar_dmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, |
| struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan); |
| |
| /* Someone calling slave DMA on a generic channel? */ |
| - if (rchan->mid_rid < 0 || !sg_len) { |
| + if (rchan->mid_rid < 0 || !sg_len || !sg_dma_len(sgl)) { |
| dev_warn(chan->device->dev, |
| "%s: bad parameter: len=%d, id=%d\n", |
| __func__, sg_len, rchan->mid_rid); |
| -- |
| 2.20.1 |
| |
