linux-kernel - [PATCH AUTOSEL 4.19 15/27] dmaengine: stm32-mdma: Fix a possible null-pointer dereference in stm32_mdma_irq

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Message-Id: <20190820134213.11279-15-sashal@kernel.org>
Date:   Tue, 20 Aug 2019 09:42:01 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jia-Ju Bai <baijiaju1990@...il.com>, Vinod Koul <vkoul@...nel.org>,
        Sasha Levin <sashal@...nel.org>, dmaengine@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 15/27] dmaengine: stm32-mdma: Fix a possible null-pointer dereference in stm32_mdma_irq_handler()

From: Jia-Ju Bai <baijiaju1990@...il.com>

[ Upstream commit 39c71a5b8212f4b502d9a630c6706ac723abd422 ]

In stm32_mdma_irq_handler(), chan is checked on line 1368.
When chan is NULL, it is still used on line 1369:
    dev_err(chan2dev(chan), "MDMA channel not initialized\n");

Thus, a possible null-pointer dereference may occur.

To fix this bug, "dev_dbg(mdma2dev(dmadev), ...)" is used instead.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Fixes: a4ffb13c8946 ("dmaengine: Add STM32 MDMA driver")
Link: https://lore.kernel.org/r/20190729020849.17971-1-baijiaju1990@gmail.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/dma/stm32-mdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index 06dd1725375e5..8c3c3e5b812a8 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -1376,7 +1376,7 @@ static irqreturn_t stm32_mdma_irq_handler(int irq, void *devid)
 
 	chan = &dmadev->chan[id];
 	if (!chan) {
-		dev_err(chan2dev(chan), "MDMA channel not initialized\n");
+		dev_dbg(mdma2dev(dmadev), "MDMA channel not initialized\n");
 		goto exit;
 	}
 
-- 
2.20.1