CVE-2025-37890 net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc

In the Linux kernel, the following vulnerability has been resolved: netsched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report 1, we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that...

kernel: net/sched: sch_hfsc UAF

A use-after-free flaw was found in the Linux kernel's net/sched: schhfsc HFSC qdisc traffic control component that can be exploited to achieve local privilege escalation. If a class with a link-sharing curve, for example, with the HFSCFSC flag set, has a parent without a link-sharing curve, then...