linux-kernel - [PATCH] mtd: spi-nor: fix memory leak when using debugfs

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Date:   Fri,  2 Sep 2022 15:37:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     tudor.ambarus@...rochip.com, pratyush@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michael Walle <michael@...le.cc>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, stable <stable@...nel.org>
Subject: [PATCH] mtd: spi-nor: fix memory leak when using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  Fix this up to be much
simpler logic and only create the root debugfs directory once when the
driver is first accessed.  That resolves the memory leak and makes
things more obvious as to what the intent is.

Cc: Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc: Pratyush Yadav <pratyush@...nel.org>
Cc: Michael Walle <michael@...le.cc>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Richard Weinberger <richard@....at>
Cc: Vignesh Raghavendra <vigneshr@...com>
Cc: linux-mtd@...ts.infradead.org
Cc: stable <stable@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/mtd/spi-nor/debugfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index df76cb5de3f9..3aab595e82d1 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -228,11 +228,11 @@ static void spi_nor_debugfs_unregister(void *data)
 
 void spi_nor_debugfs_register(struct spi_nor *nor)
 {
-	struct dentry *rootdir, *d;
+	static struct dentry *rootdir;
+	struct dentry *d;
 	int ret;
 
 	/* Create rootdir once. Will never be deleted again. */
-	rootdir = debugfs_lookup(SPI_NOR_DEBUGFS_ROOT, NULL);
 	if (!rootdir)
 		rootdir = debugfs_create_dir(SPI_NOR_DEBUGFS_ROOT, NULL);
 
-- 
2.37.3