bcache: properly initialize 'path' and 'err' in register_bcache()

[ 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>

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 485ebc2..658b0f4 100644 (file)
--- 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;