In the Linux kernel, the following vulnerability has been resolved: ovl: fix warning in ovlcreatereal() Syzbot triggered the following warning in ovlworkdircreate() -> ovlcreatereal(): if (!err && WARNON(!newdentry->dinode)) { The reason is that the cgroup2 filesystem returns from mkdir without instantiating the new dentry. Weird filesystems such as this will be rejected by overlayfs at a later stage during setup, but to prevent such a warning, call ovlmkdirreal() directly from ovlworkdircreate() and reject this case early.