From 04204cd9b0b450bfe561a5f8d0fc91288c6427ab Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Thu, 1 Feb 2024 12:33:46 -0500 Subject: eventfs: Add WARN_ON_ONCE() to checks in eventfs_root_lookup() There's a couple of if statements in eventfs_root_lookup() that should never be true. Instead of removing them, add WARN_ON_ONCE() around them. One is a tracefs_inode not being for eventfs. The other is a child being freed but still on the parent's children list. When a child is freed, it is removed from the list under the same mutex that is held during the iteration. Link: https://lore.kernel.org/linux-trace-kernel/20240201002719.GS2087318@ZenIV/ Link: https://lore.kernel.org/linux-trace-kernel/20240201123346.724afa46@gandalf.local.home Cc: Linus Torvalds Cc: Al Viro Cc: Christian Brauner Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Mark Rutland Cc: Ajay Kaher Reported-by: Al Viro Signed-off-by: Steven Rostedt (Google) --- fs/tracefs/event_inode.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 110e8a272189..9d9c7dc3114b 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -483,7 +483,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *result = NULL; ti = get_tracefs(dir); - if (!(ti->flags & TRACEFS_EVENT_INODE)) + if (WARN_ON_ONCE(!(ti->flags & TRACEFS_EVENT_INODE))) return ERR_PTR(-EIO); mutex_lock(&eventfs_mutex); @@ -495,7 +495,8 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, list_for_each_entry(ei_child, &ei->children, list) { if (strcmp(ei_child->name, name) != 0) continue; - if (ei_child->is_freed) + /* A child is freed and removed from the list at the same time */ + if (WARN_ON_ONCE(ei_child->is_freed)) goto out; result = lookup_dir_entry(dentry, ei, ei_child); goto out; -- cgit v1.2.3