locks: fix a memory leak bug in __break_lease()

mainline inclusion
from mainline-5.4-rc1
commit cfddf9f4
category: bugfix
bugzilla: 21612
CVE: NA

---------------------------

In __break_lease(), the file lock 'new_fl' is allocated in lease_alloc().
However, it is not deallocated in the following execution if
smp_load_acquire() fails, leading to a memory leak bug. To fix this issue,
free 'new_fl' before returning the error.

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>

fs/locks.c

@@ -1459,7 +1459,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 	ctx = smp_load_acquire(&inode->i_flctx);
 	if (!ctx) {
 		WARN_ON_ONCE(1);
-		return error;
+		goto free_lock;
 	}
 
 	percpu_down_read_preempt_disable(&file_rwsem);
@@ -1539,6 +1539,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 	spin_unlock(&ctx->flc_lock);
 	percpu_up_read_preempt_enable(&file_rwsem);
 	locks_dispose_list(&dispose);
+free_lock:
 	locks_free_lock(new_fl);
 	return error;
 }