In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class handling This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class handling. The issue occurs due to a time-of-check/time-of-use condition in hfsc_change_class() when working with certain child qdiscs like netem or codel. The vulnerability works as follows: 1. hfsc_change_class() checks if a class has packets (q.qlen != 0) 2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g., codel, netem) might drop packets and empty the queue 3. The code continues assuming the queue is still non-empty, adding the class to vttree 4. This breaks HFSC scheduler assumptions that only non-empty classes are in vttree 5. Later, when the class is destroyed, this can lead to a Use-After-Free The fix adds a second queue length check after qdisc_peek_len() to verify the queue wasn't emptied.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2025050210-CVE-2025-37797-2aab@gregkh/T
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2025:11855 https://access.redhat.com/errata/RHSA-2025:11855
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:11861 https://access.redhat.com/errata/RHSA-2025:11861
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2025:13633 https://access.redhat.com/errata/RHSA-2025:13633
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Via RHSA-2025:13781 https://access.redhat.com/errata/RHSA-2025:13781
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.4 Extended Update Support Via RHSA-2025:13946 https://access.redhat.com/errata/RHSA-2025:13946
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2025:14054 https://access.redhat.com/errata/RHSA-2025:14054
This issue has been addressed in the following products: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions Via RHSA-2025:14094 https://access.redhat.com/errata/RHSA-2025:14094
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2025:16920 https://access.redhat.com/errata/RHSA-2025:16920
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2025:16919 https://access.redhat.com/errata/RHSA-2025:16919
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Red Hat Enterprise Linux 8.8 Telecommunications Update Service Via RHSA-2025:18932 https://access.redhat.com/errata/RHSA-2025:18932
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions Red Hat Enterprise Linux 8.6 Telecommunications Update Service Via RHSA-2025:19222 https://access.redhat.com/errata/RHSA-2025:19222