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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Wen Yang <wenyang@linux.alibaba.com>,
        Joern Engel <joern@lazybastard.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-mtd@lists.infradead.org
Subject: [PATCH 5.6 161/166] mtd: phram: fix a double free issue in error path
Date:   Wed, 22 Apr 2020 11:58:08 +0200
Message-Id: <20200422095105.674074170@linuxfoundation.org>
In-Reply-To: <20200422095047.669225321@linuxfoundation.org>
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From: Wen Yang <wenyang@linux.alibaba.com>

commit 49c64df880570034308e4a9a49c4bc95cf8cdb33 upstream.

The variable 'name' is released multiple times in the error path,
which may cause double free issues.
This problem is avoided by adding a goto label to release the memory
uniformly. And this change also makes the code a bit more cleaner.

Fixes: 4f678a58d335 ("mtd: fix memory leaks in phram_setup")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Joern Engel <joern@lazybastard.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200318153156.25612-1-wenyang@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mtd/devices/phram.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -243,22 +243,25 @@ static int phram_setup(const char *val)
 
 	ret = parse_num64(&start, token[1]);
 	if (ret) {
-		kfree(name);
 		parse_err("illegal start address\n");
+		goto error;
 	}
 
 	ret = parse_num64(&len, token[2]);
 	if (ret) {
-		kfree(name);
 		parse_err("illegal device length\n");
+		goto error;
 	}
 
 	ret = register_device(name, start, len);
-	if (!ret)
-		pr_info("%s device: %#llx at %#llx\n", name, len, start);
-	else
-		kfree(name);
+	if (ret)
+		goto error;
 
+	pr_info("%s device: %#llx at %#llx\n", name, len, start);
+	return 0;
+
+error:
+	kfree(name);
 	return ret;
 }