linux-kernel - [PATCH] mtd: nxp-spifi: decrement flash

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Date:   Tue,  8 May 2018 23:47:36 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Joachim Eastwood <manabian@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Richard Weinberger <richard@....at>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org, Julia Lawall <julia.lawall@...6.fr>,
        sil2review@...ts.osadl.org
Subject: [PATCH] mtd: nxp-spifi: decrement flash_np refcnt on error paths

nxp_spifi_probe() increments refcnt of SPI flash device node by
of_get_next_available_child() and then it passes the node
to mtd device in nxp_spifi_setup_flash().
But if a failure happens before mtd_device_register() succeed,
the refcnt is left undecremented.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
---
 drivers/mtd/spi-nor/nxp-spifi.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/spi-nor/nxp-spifi.c b/drivers/mtd/spi-nor/nxp-spifi.c
index 15374216d4d9..8919e31f2ab8 100644
--- a/drivers/mtd/spi-nor/nxp-spifi.c
+++ b/drivers/mtd/spi-nor/nxp-spifi.c
@@ -294,7 +294,8 @@ static int nxp_spifi_setup_flash(struct nxp_spifi *spifi,
 			break;
 		default:
 			dev_err(spifi->dev, "unsupported rx-bus-width\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto err_node_put;
 		}
 	}
 
@@ -328,7 +329,8 @@ static int nxp_spifi_setup_flash(struct nxp_spifi *spifi,
 		break;
 	default:
 		dev_err(spifi->dev, "only mode 0 and 3 supported\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto err_node_put;
 	}
 
 	writel(ctrl, spifi->io_base + SPIFI_CTRL);
@@ -356,22 +358,26 @@ static int nxp_spifi_setup_flash(struct nxp_spifi *spifi,
 	ret = spi_nor_scan(&spifi->nor, NULL, &hwcaps);
 	if (ret) {
 		dev_err(spifi->dev, "device scan failed\n");
-		return ret;
+		goto err_node_put;
 	}
 
 	ret = nxp_spifi_setup_memory_cmd(spifi);
 	if (ret) {
 		dev_err(spifi->dev, "memory command setup failed\n");
-		return ret;
+		goto err_node_put;
 	}
 
 	ret = mtd_device_register(&spifi->nor.mtd, NULL, 0);
 	if (ret) {
 		dev_err(spifi->dev, "mtd device parse failed\n");
-		return ret;
+		goto err_node_put;
 	}
 
 	return 0;
+
+err_node_put:
+	of_node_put(np);
+	return ret;
 }
 
 static int nxp_spifi_probe(struct platform_device *pdev)
-- 
2.7.4