2019-08-19 23:48:44

by Wenwen Wang

Subject: [PATCH] locks: fix a memory leak bug

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 <[email protected]>
---
fs/locks.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/locks.c b/fs/locks.c
index 686eae2..5993b2a 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1592,7 +1592,7 @@ 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(&file_rwsem);
@@ -1672,6 +1672,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
locks_dispose_list(&dispose);
+free_lock:
locks_free_lock(new_fl);
return error;
}
--
2.7.4

2019-08-20 09:52:32

by Jeff Layton

Subject: Re: [PATCH] locks: fix a memory leak bug

On Mon, 2019-08-19 at 18:47 -0500, Wenwen Wang wrote:
> 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 <[email protected]>
> ---
> fs/locks.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 686eae2..5993b2a 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1592,7 +1592,7 @@ 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(&file_rwsem);
> @@ -1672,6 +1672,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
> spin_unlock(&ctx->flc_lock);
> percpu_up_read(&file_rwsem);
> locks_dispose_list(&dispose);
> +free_lock:
> locks_free_lock(new_fl);
> return error;
> }

Good catch! Merged for v5.4. Let me know if you think this needs to go
in earlier and/or to stable kernels.

Thanks,
--
Jeff Layton <[email protected]>