[PATCH 5.4 212/475] mtd: rawnand: atmel: fix refcount issue in atmel_nand_controller_init

From: Greg Kroah-Hartman
Date: Thu Apr 14 2022 - 10:56:55 EST


From: Xin Xiong <xiongx18@xxxxxxxxxxxx>

[ 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@xxxxxxxxxxxx>
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Co-developed-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Signed-off-by: Xin Xiong <xiongx18@xxxxxxxxxxxx>
Reviewed-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/20220304085330.3610-1-xiongx18@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/mtd/nand/raw/atmel/nand-controller.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
index 23d11e8b5644..17c751f359d3 100644
--- a/drivers/mtd/nand/raw/atmel/nand-controller.c
+++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
@@ -2004,13 +2004,15 @@ 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);
@@ -2018,10 +2020,16 @@ 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