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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, Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>,
        Xin Xiong <xiongx18@fudan.edu.cn>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 123/284] mtd: rawnand: atmel: fix refcount issue in atmel_nand_controller_init
Date:   Mon, 18 Apr 2022 14:11:44 +0200
Message-Id: <20220418121214.658422150@linuxfoundation.org>
In-Reply-To: <20220418121210.689577360@linuxfoundation.org>
References: <20220418121210.689577360@linuxfoundation.org>
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From: Xin Xiong <xiongx18@fudan.edu.cn>

[ Upstream commit fecbd4a317c95d73c849648c406bcf1b6a0ec1cf ]

The reference counting issue happens in several error handling paths
on a refcounted object "nc->dmac". In these paths, the function simply
returns the error code, forgetting to balance the reference count of
"nc->dmac", increased earlier by dma_request_channel(), which may
cause refcount leaks.

Fix it by decrementing the refcount of specific object in those error
paths.

Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Co-developed-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Co-developed-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220304085330.3610-1-xiongx18@fudan.edu.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mtd/nand/atmel/nand-controller.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/atmel/nand-controller.c b/drivers/mtd/nand/atmel/nand-controller.c
index d5a493e8ee08..475c751f2d1e 100644
--- a/drivers/mtd/nand/atmel/nand-controller.c
+++ b/drivers/mtd/nand/atmel/nand-controller.c
@@ -1998,13 +1998,15 @@ static int atmel_nand_controller_init(struct atmel_nand_controller *nc,
 	nc->mck = of_clk_get(dev->parent->of_node, 0);
 	if (IS_ERR(nc->mck)) {
 		dev_err(dev, "Failed to retrieve MCK clk\n");
-		return PTR_ERR(nc->mck);
+		ret = PTR_ERR(nc->mck);
+		goto out_release_dma;
 	}
 
 	np = of_parse_phandle(dev->parent->of_node, "atmel,smc", 0);
 	if (!np) {
 		dev_err(dev, "Missing or invalid atmel,smc property\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out_release_dma;
 	}
 
 	nc->smc = syscon_node_to_regmap(np);
@@ -2012,10 +2014,16 @@ static int atmel_nand_controller_init(struct atmel_nand_controller *nc,
 	if (IS_ERR(nc->smc)) {
 		ret = PTR_ERR(nc->smc);
 		dev_err(dev, "Could not get SMC regmap (err = %d)\n", ret);
-		return ret;
+		goto out_release_dma;
 	}
 
 	return 0;
+
+out_release_dma:
+	if (nc->dmac)
+		dma_release_channel(nc->dmac);
+
+	return ret;
 }
 
 static int
-- 
2.34.1