CVE-2023-3609 Use-after-free in Linux kernel's net/sched: cls_u32 component

A use-after-free vulnerability in the Linux kernel’s net/sched: cls_u32 component can be exploited to achieve local privilege escalation.

If tcf_change_indev() fails, u32_set_parms() will immediately return an error after incrementing or decrementing the reference counter in tcf_bind_filter(). If an attacker can control the reference counter and set it to zero, they can cause the reference to be freed, leading to a use-after-free vulnerability.

We recommend upgrading past commit 04c55383fa5689357bcdd2c8036725a55ed632bc.