linux-kernel - [PATCH] mtd: rawnand: atmel: fix refcount leaks in atmel_nand_controller

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Date:   Tue, 25 Jan 2022 20:31:56 +0800
From:   Xin Xiong <xiongx18@...an.edu.cn>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, Xin Xiong <xiongx18@...an.edu.cn>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] mtd: rawnand: atmel: fix refcount leaks in atmel_nand_controller_init

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
increased earlier by dma_request_channel(), which may cause refcount
leaks. What's more, the "nc->mck" object also needs to be handled
correctly.

Fix it by adding specific error handling code in those error paths.

Signed-off-by: Xin Xiong <xiongx18@...an.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 drivers/mtd/nand/raw/atmel/nand-controller.c | 22 +++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
index f3276ee9e..b3801ebd2 100644
--- a/drivers/mtd/nand/raw/atmel/nand-controller.c
+++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
@@ -2060,13 +2060,15 @@ 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_put_clk;
 	}
 
 	nc->smc = syscon_node_to_regmap(np);
@@ -2074,10 +2076,24 @@ 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_put_clk;
 	}
 
 	return 0;
+
+out_put_clk:
+	clk_put(nc->mck);
+	nc->mck = NULL;
+
+out_release_dma:
+	if (nc->caps->has_dma && !atmel_nand_avoid_dma) {
+		if (!IS_ERR_OR_NULL(nc->dmac)) {
+			dma_release_channel(nc->dmac);
+			nc->dmac = NULL;
+		}
+	}
+
+	return ret;
 }
 
 static int
-- 
2.25.1