From 78efb76ab4dfb8f74f290ae743f34162cd627f19 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 24 Jun 2019 14:38:18 +0200 Subject: dmaengine: rcar-dmac: Reject zero-length slave DMA requests 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 Analyzed-by: Yoshihiro Shimoda Signed-off-by: Geert Uytterhoeven Signed-off-by: Vinod Koul --- drivers/dma/sh/rcar-dmac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/dma/sh') diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 67df54ac3294..9c41a4e42575 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1165,7 +1165,7 @@ 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); -- cgit v1.2.1