From 020010fbfa202aa528a52743eba4ab0da3400a4e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 1 Nov 2023 13:25:47 -0400 Subject: eventfs: Delete eventfs_inode when the last dentry is freed There exists a race between holding a reference of an eventfs_inode dentry and the freeing of the eventfs_inode. If user space has a dentry held long enough, it may still be able to access the dentry's eventfs_inode after it has been freed. To prevent this, have he eventfs_inode freed via the last dput() (or via RCU if the eventfs_inode does not have a dentry). This means reintroducing the eventfs_inode del_list field at a temporary place to put the eventfs_inode. It needs to mark it as freed (via the list) but also must invalidate the dentry immediately as the return from eventfs_remove_dir() expects that they are. But the dentry invalidation must not be called under the eventfs_mutex, so it must be done after the eventfs_inode is marked as free (put on a deletion list). Link: https://lkml.kernel.org/r/20231101172650.123479767@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Andrew Morton Cc: Ajay Kaher Fixes: 5bdcd5f5331a2 ("eventfs: Implement removal of meta data from eventfs") Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/internal.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/tracefs/internal.h') diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 5f60bcd69289..06a1f220b901 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -54,10 +54,12 @@ struct eventfs_inode { void *data; /* * Union - used for deletion + * @llist: for calling dput() if needed after RCU * @del_list: list of eventfs_inode to delete * @rcu: eventfs_inode to delete in RCU */ union { + struct llist_node llist; struct list_head del_list; struct rcu_head rcu; }; -- cgit v1.2.3