linux-kernel - [PATCH v2] dmaengine: mmp_tdma: Validate the transfer direction

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Message-Id: <20200424215020.105281-1-lkundrak@v3.sk>
Date:   Fri, 24 Apr 2020 23:50:20 +0200
From:   Lubomir Rintel <lkundrak@...sk>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Lubomir Rintel <lkundrak@...sk>
Subject: [PATCH v2] dmaengine: mmp_tdma: Validate the transfer direction

We only support DMA_DEV_TO_MEM and DMA_MEM_TO_DEV. Let's not do
undefined things with other values and reject them.

Signed-off-by: Lubomir Rintel <lkundrak@...sk>
---
Changes since v1:
- Replace the extra validation with is_slave_direction() in
  _prep_dma_cyclic(), as Vinod Koul suggested.

 drivers/dma/mmp_tdma.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/dma/mmp_tdma.c b/drivers/dma/mmp_tdma.c
index 8947e4832ca3..dbc6a48424fa 100644
--- a/drivers/dma/mmp_tdma.c
+++ b/drivers/dma/mmp_tdma.c
@@ -429,6 +429,11 @@ static struct dma_async_tx_descriptor *mmp_tdma_prep_dma_cyclic(
 	int num_periods = buf_len / period_len;
 	int i = 0, buf = 0;
 
+	if (!is_slave_direction(direction)) {
+		dev_err(tdmac->dev, "unsupported transfer direction\n");
+		return NULL;
+	}
+
 	if (tdmac->status != DMA_COMPLETE) {
 		dev_err(tdmac->dev, "controller busy");
 		return NULL;
-- 
2.26.0