linux-kernel - [PATCH 5.5 399/399] bcache: properly initialize path and err in register

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Message-Id: <20200221072438.575910308@linuxfoundation.org>
Date:   Fri, 21 Feb 2020 08:42:04 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Coly Li <colyli@...e.de>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.5 399/399] bcache: properly initialize path and err in register_bcache()

From: Coly Li <colyli@...e.de>

[ Upstream commit 29cda393bcaad160c4bf3676ddd99855adafc72f ]

Patch "bcache: rework error unwinding in register_bcache" from
Christoph Hellwig changes the local variables 'path' and 'err'
in undefined initial state. If the code in register_bcache() jumps
to label 'out:' or 'out_module_put:' by goto, these two variables
might be reference with undefined value by the following line,

	out_module_put:
	        module_put(THIS_MODULE);
	out:
	        pr_info("error %s: %s", path, err);
	        return ret;

Therefore this patch initializes these two local variables properly
in register_bcache() to avoid such issue.

Signed-off-by: Coly Li <colyli@...e.de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/md/bcache/super.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 05cb94664efee..3b3724285d907 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -2376,18 +2376,20 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 			       const char *buffer, size_t size)
 {
 	const char *err;
-	char *path;
+	char *path = NULL;
 	struct cache_sb *sb;
 	struct block_device *bdev = NULL;
 	struct page *sb_page;
 	ssize_t ret;
 
 	ret = -EBUSY;
+	err = "failed to reference bcache module";
 	if (!try_module_get(THIS_MODULE))
 		goto out;
 
 	/* For latest state of bcache_is_reboot */
 	smp_mb();
+	err = "bcache is in reboot";
 	if (bcache_is_reboot)
 		goto out_module_put;
 
-- 
2.20.1