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From: "M'boumba Cedric Madianga" <cedric.madianga@gmail.com>
To: vinod.koul@intel.com, dan.j.williams@intel.com,
	mcoquelin.stm32@gmail.com, dmaengine@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Cc: "M'boumba Cedric Madianga" <cedric.madianga@gmail.com>
Subject: [PATCH v2] dmaengine: stm32-dma: Fix unchecked deference of chan->desc
Date: Mon,  7 Dec 2015 12:00:28 +0100	[thread overview]
Message-ID: <1449486028-29344-1-git-send-email-cedric.madianga@gmail.com> (raw)

'commit d8b468394fb7 ("dmaengine: Add STM32 DMA driver")' leads to the
following Smatch complaint:

drivers/dma/stm32-dma.c:562 stm32_dma_issue_pending()
    error: we previously assumed 'chan->desc' could be null (see line 560)

So, this patch fixes the unchecked dereference of chan->desc by returning
operation not permitted error when stm32_dma_start_transfer() does not
succeed to allocate a virtual channel descriptor.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>

---
Changes since v1:
Explain what the patch fixes in the title (Vinod)
Add Dan as reporter using Reported-by tag (Vinod)
---
---
 drivers/dma/stm32-dma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 12f3a3e..047476a 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -437,7 +437,7 @@ static int stm32_dma_start_transfer(struct stm32_dma_chan *chan)
 	if (!chan->desc) {
 		vdesc = vchan_next_desc(&chan->vchan);
 		if (!vdesc)
-			return 0;
+			return -EPERM;
 
 		chan->desc = to_stm32_dma_desc(vdesc);
 		chan->next_sg = 0;
@@ -559,7 +559,7 @@ static void stm32_dma_issue_pending(struct dma_chan *c)
 	if (!chan->busy) {
 		if (vchan_issue_pending(&chan->vchan) && !chan->desc) {
 			ret = stm32_dma_start_transfer(chan);
-			if ((chan->desc->cyclic) && (!ret))
+			if ((!ret) && (chan->desc->cyclic))
 				stm32_dma_configure_next_sg(chan);
 		}
 	}
-- 
1.9.1


WARNING: multiple messages have this Message-ID (diff)
From: cedric.madianga@gmail.com (M'boumba Cedric Madianga)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] dmaengine: stm32-dma: Fix unchecked deference of chan->desc
Date: Mon,  7 Dec 2015 12:00:28 +0100	[thread overview]
Message-ID: <1449486028-29344-1-git-send-email-cedric.madianga@gmail.com> (raw)

'commit d8b468394fb7 ("dmaengine: Add STM32 DMA driver")' leads to the
following Smatch complaint:

drivers/dma/stm32-dma.c:562 stm32_dma_issue_pending()
    error: we previously assumed 'chan->desc' could be null (see line 560)

So, this patch fixes the unchecked dereference of chan->desc by returning
operation not permitted error when stm32_dma_start_transfer() does not
succeed to allocate a virtual channel descriptor.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>

---
Changes since v1:
Explain what the patch fixes in the title (Vinod)
Add Dan as reporter using Reported-by tag (Vinod)
---
---
 drivers/dma/stm32-dma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 12f3a3e..047476a 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -437,7 +437,7 @@ static int stm32_dma_start_transfer(struct stm32_dma_chan *chan)
 	if (!chan->desc) {
 		vdesc = vchan_next_desc(&chan->vchan);
 		if (!vdesc)
-			return 0;
+			return -EPERM;
 
 		chan->desc = to_stm32_dma_desc(vdesc);
 		chan->next_sg = 0;
@@ -559,7 +559,7 @@ static void stm32_dma_issue_pending(struct dma_chan *c)
 	if (!chan->busy) {
 		if (vchan_issue_pending(&chan->vchan) && !chan->desc) {
 			ret = stm32_dma_start_transfer(chan);
-			if ((chan->desc->cyclic) && (!ret))
+			if ((!ret) && (chan->desc->cyclic))
 				stm32_dma_configure_next_sg(chan);
 		}
 	}
-- 
1.9.1

             reply	other threads:[~2015-12-07 11:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-07 11:00 M'boumba Cedric Madianga [this message]
2015-12-07 11:00 ` [PATCH v2] dmaengine: stm32-dma: Fix unchecked deference of chan->desc M'boumba Cedric Madianga
2015-12-10  4:15 ` Vinod Koul
2015-12-10  4:15   ` Vinod Koul

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