btrfs: fix uninitialized pointer free in add_inode_ref()

The add_inode_ref() function does not initialize the "name" struct when
it is declared.  If any of the following calls to "read_one_inode()
returns NULL,

	dir = read_one_inode(root, parent_objectid);
	if (!dir) {
		ret = -ENOENT;
		goto out;
	}

	inode = read_one_inode(root, inode_objectid);
	if (!inode) {
		ret = -EIO;
		goto out;
	}

then "name.name" would be freed on "out" before being initialized.

out:
	...
	kfree(name.name);

This issue was reported by Coverity with CID 1526744.

Fixes: e43eec81 ("btrfs: use struct qstr instead of name and namelen pairs")
CC: stable@vger.kernel.org # 6.6+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Roi Martin <jroi.martin@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -1374,7 +1374,7 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
 	struct inode *inode = NULL;
 	unsigned long ref_ptr;
 	unsigned long ref_end;
-	struct fscrypt_str name;
+	struct fscrypt_str name = { 0 };
 	int ret;
 	int log_ref_ver = 0;
 	u64 parent_objectid;