[PATCH AUTOSEL 4.19 69/83] afs: Fix key refcounting in file locking code

Sasha Levin
2019-02-13T02:39:28Z

From: David Howells <dhowells@redhat.com>

[ Upstream commit 59d49076ae3e6912e6d7df2fd68e2337f3d02036 ]

Fix the refcounting of the authentication keys in the file locking code.
The vnode->lock_key member points to a key on which it expects to be
holding a ref, but it isn't always given an extra ref, however.

Fixes: 0fafdc9f888b ("afs: Fix file locking")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/afs/flock.c | 4 ++--
fs/afs/inode.c | 2 ++
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/afs/flock.c b/fs/afs/flock.c
index dc62d15a964b..1bb300ef362b 100644
--- a/fs/afs/flock.c
+++ b/fs/afs/flock.c
@@ -208,7 +208,7 @@ void afs_lock_work(struct work_struct *work)
/* The new front of the queue now owns the state variables. */
next = list_entry(vnode->pending_locks.next,
struct file_lock, fl_u.afs.link);
- vnode->lock_key = afs_file_key(next->fl_file);
+ vnode->lock_key = key_get(afs_file_key(next->fl_file));
vnode->lock_type = (next->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
vnode->lock_state = AFS_VNODE_LOCK_WAITING_FOR_CB;
goto again;
@@ -413,7 +413,7 @@ static void afs_dequeue_lock(struct afs_vnode *vnode, struct file_lock *fl)
/* The new front of the queue now owns the state variables. */
next = list_entry(vnode->pending_locks.next,
struct file_lock, fl_u.afs.link);
- vnode->lock_key = afs_file_key(next->fl_file);
+ vnode->lock_key = key_get(afs_file_key(next->fl_file));
vnode->lock_type = (next->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
vnode->lock_state = AFS_VNODE_LOCK_WAITING_FOR_CB;
afs_lock_may_be_available(vnode);
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 26aa2d111a28..0726e40db0f8 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -542,6 +542,8 @@ void afs_evict_inode(struct inode *inode)
#endif

afs_put_permits(rcu_access_pointer(vnode->permit_cache));
+ key_put(vnode->lock_key);
+ vnode->lock_key = NULL;
_leave("");
}

--
2.19.1