mtd: rawnand: atmel: fix refcount issue in atmel_nand_controller_init

[ 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>

diff --git a/drivers/mtd/nand/atmel/nand-controller.c b/drivers/mtd/nand/atmel/nand-controller.c
index d5a493e8ee08365913ef5dfe4e3ab57daf63cc01..475c751f2d1e2aec1fab890c56abac4e4859f490 100644 (file)
--- 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