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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Baolin Wang <baolin.wang@linaro.org>,
        Vinod Koul <vkoul@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.1 037/121] dmaengine: sprd: Add validation of current descriptor in irq handler
Date:   Mon, 24 Jun 2019 17:56:09 +0800
Message-Id: <20190624092322.707315593@linuxfoundation.org>
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[ Upstream commit 58152b0e573e5581c4b9ef7cf06d2e9fafae27d4 ]

When user terminates one DMA channel to free all its descriptors, but
at the same time one transaction interrupt was triggered possibly, now
we should not handle this interrupt by validating if the 'schan->cur_desc'
was set as NULL to avoid crashing the kernel.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/sprd-dma.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
index e29342ab85f6..431e289d59a5 100644
--- a/drivers/dma/sprd-dma.c
+++ b/drivers/dma/sprd-dma.c
@@ -552,12 +552,17 @@ static irqreturn_t dma_irq_handle(int irq, void *dev_id)
 		schan = &sdev->channels[i];
 
 		spin_lock(&schan->vc.lock);
+
+		sdesc = schan->cur_desc;
+		if (!sdesc) {
+			spin_unlock(&schan->vc.lock);
+			return IRQ_HANDLED;
+		}
+
 		int_type = sprd_dma_get_int_type(schan);
 		req_type = sprd_dma_get_req_type(schan);
 		sprd_dma_clear_int(schan);
 
-		sdesc = schan->cur_desc;
-
 		/* cyclic mode schedule callback */
 		cyclic = schan->linklist.phy_addr ? true : false;
 		if (cyclic == true) {
-- 
2.20.1