linux-kernel - [PATCH 1/3] dmaengine: zynqmp_dma: In struct zynqmp_dma_chan fix desc

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Date:   Tue, 10 May 2022 12:42:40 +0530
From:   Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
To:     <vkoul@...nel.org>
CC:     <michal.simek@...inx.com>, <dmaengine@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <git@...inx.com>,
        Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
Subject: [PATCH 1/3] dmaengine: zynqmp_dma: In struct zynqmp_dma_chan fix desc_size data type

In zynqmp_dma_alloc/free_chan_resources functions there is a
potential overflow in the below expressions.

dma_alloc_coherent(chan->dev, (2 * chan->desc_size *
		   ZYNQMP_DMA_NUM_DESCS),
		   &chan->desc_pool_p, GFP_KERNEL);

dma_free_coherent(chan->dev,(2 * ZYNQMP_DMA_DESC_SIZE(chan) *
                 ZYNQMP_DMA_NUM_DESCS),
                chan->desc_pool_v, chan->desc_pool_p);

The arguments desc_size and ZYNQMP_DMA_NUM_DESCS were 32 bit. Though
this overflow condition is not observed but it is a potential problem
in the case of 32-bit multiplication. Hence fix it by changing the
desc_size data type to size_t.

In addition to coverity fix it also reuse ZYNQMP_DMA_DESC_SIZE macro in
dma_alloc_coherent API argument.

Addresses-Coverity: Event overflow_before_widen.
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
---
 drivers/dma/xilinx/zynqmp_dma.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
index 7aa63b652027..3ffa7f37c701 100644
--- a/drivers/dma/xilinx/zynqmp_dma.c
+++ b/drivers/dma/xilinx/zynqmp_dma.c
@@ -229,7 +229,7 @@ struct zynqmp_dma_chan {
 	bool is_dmacoherent;
 	struct tasklet_struct tasklet;
 	bool idle;
-	u32 desc_size;
+	size_t desc_size;
 	bool err;
 	u32 bus_width;
 	u32 src_burst_len;
@@ -486,7 +486,8 @@ static int zynqmp_dma_alloc_chan_resources(struct dma_chan *dchan)
 	}
 
 	chan->desc_pool_v = dma_alloc_coherent(chan->dev,
-					       (2 * chan->desc_size * ZYNQMP_DMA_NUM_DESCS),
+					       (2 * ZYNQMP_DMA_DESC_SIZE(chan) *
+					       ZYNQMP_DMA_NUM_DESCS),
 					       &chan->desc_pool_p, GFP_KERNEL);
 	if (!chan->desc_pool_v)
 		return -ENOMEM;
-- 
2.25.1