* [PATCH AUTOSEL 4.4 05/23] dmaengine: rcar-dmac: Reject zero-length slave DMA requests
[not found] <20190726134522.13308-1-sashal@kernel.org>
@ 2019-07-26 13:45 ` Sasha Levin
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From: Sasha Levin @ 2019-07-26 13:45 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Geert Uytterhoeven, Eugeniu Rosca, Yoshihiro Shimoda, Vinod Koul,
Sasha Levin, dmaengine
From: Geert Uytterhoeven <geert+renesas@glider.be>
[ 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 2b36d1c63aa5..956189a1ba81 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1030,7 +1030,7 @@ rcar_dmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
dma_addr_t dev_addr;
/* 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
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