[PATCH 5.4 344/344] bcache: properly initialize path and err in register_bcache()

Greg Kroah-Hartman
2020-02-21T08:16:20Z

From: Coly Li <colyli@suse.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@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.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 485ebc2b2144c..658b0f4a01f56 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -2373,18 +2373,20 @@ 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