linux-kernel - [PATCH] mtd: phram: fix a double free issue in error path

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Date:   Wed, 18 Mar 2020 23:27:48 +0800
From:   Wen Yang <wenyang@...ux.alibaba.com>
To:     Joern Engel <joern@...ybastard.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Cc:     Wen Yang <wenyang@...ux.alibaba.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mtd: phram: fix a double free issue in error path

The variable 'name' is released multiple times in the error path,
which may cause double.
This problem is avoided by adding a goto label to release memory
uniformly. 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@...ux.alibaba.com>
Cc: Joern Engel <joern@...ybastard.org>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Richard Weinberger <richard@....at>
Cc: Vignesh Raghavendra <vigneshr@...com>
Cc: linux-mtd@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/mtd/devices/phram.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index 931e5c2481b5..b50ec7ecd10c 100644
--- 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;
 }
 
-- 
2.23.0