On Sonntag, 12. November 2023 18:18:17 CET Steven Rostedt wrote:

From: "Steven Rostedt (Google)" rostedt@goodmis.org

The top level events directory dentry does not have a d_fsdata set to a eventfs_file pointer. This dentry is still passed to eventfs_set_attr(). It can not assume that the d_fsdata is set. Check for that.

Link: https://lore.kernel.org/all/20231112104158.6638-1-milian.wolff@kdab.com/

Thanks you Steven,

this works like a charm.

Tested-by: Milian Wolff milian.wolff@kdab.com

Fixes: 9aaee3eebc91 ("eventfs: Save ownership and mode") Reported-by: Milian Wolff milian.wolff@kdab.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

---

Note: This only affects 6.6 as the code in 6.7 here was rewritten. I tested 6.7 and it does not have this bug.

fs/tracefs/event_inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 5fcfb634fec2..efbdc47c74dc 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -113,14 +113,14 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,

mutex_lock(&eventfs_mutex); ef = dentry->d_fsdata;

• if (ef->is_freed) {

• if (ef && ef->is_freed) { /* Do not allow changes if the event is about to be

removed. */

mutex_unlock(&eventfs_mutex);
return -ENODEV;

}

ret = simple_setattr(idmap, dentry, iattr);

• if (!ret)

• if (!ret && ef) update_attr(ef, iattr); mutex_unlock(&eventfs_mutex); return ret;