linux-kernel - [PATCH 4/6] afs: Fix key refcounting in file locking code

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Message-ID: <154773887782.24105.4322577070607935352.stgit@warthog.procyon.org.uk>
Date:   Thu, 17 Jan 2019 15:27:57 +0000
From:   David Howells <dhowells@...hat.com>
To:     torvalds@...ux-foundation.org
Cc:     dhowells@...hat.com, linux-afs@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] afs: Fix key refcounting in file locking code

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@...hat.com>
---

 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 0568fd986821..e432bd27a2e7 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 211343831c30..1a4ce07fb406 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -545,6 +545,8 @@ 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("");
 }