diff mbox series

[4.19.y,27/60] dmaengine: rcar-dmac: Reject zero-length slave DMA requests

Message ID 1566990211-24785-28-git-send-email-fabrizio.castro@bp.renesas.com (mailing list archive)
State Changes Requested
Headers show
Series Add basic RZ/G2M SoC support | expand

Commit Message

Fabrizio Castro Aug. 28, 2019, 11:02 a.m. UTC 
From: Geert Uytterhoeven <geert+renesas@glider.be>

commit 78efb76ab4dfb8f74f290ae743f34162cd627f19 upstream.

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: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
---
 drivers/dma/sh/rcar-dmac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 99ee8bf..cf71a73 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);