Public on 2023-09-06
Modified on 2024-01-12
A use-after-free vulnerability in the Linux kernel's net/sched: cls_u32 component can be exploited to achieve local privilege escalation.

When u32_change() is called on an existing filter, the whole tcf_result struct is always copied into the new instance of the filter. This causes a problem when updating a filter bound to a class, as tcf_unbind_filter() is always called on the old instance in the success path, decreasing filter_cnt of the still referenced class and allowing it to be deleted, leading to a use-after-free.

We recommend upgrading past commit 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81.
Important severity
CVSS v3 Base Score
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 1 kernel 2023-09-13 ALAS-2023-1827 Fixed
Amazon Linux 2 - Core kernel 2023-09-27 ALAS2-2023-2268 Fixed
Amazon Linux 2 - Kernel-5.10 Extra kernel 2023-08-31 ALAS2KERNEL-5.10-2023-039 Fixed
Amazon Linux 2 - Kernel-5.15 Extra kernel 2023-08-31 ALAS2KERNEL-5.15-2023-026 Fixed
Amazon Linux 2 - Kernel-5.4 Extra kernel 2023-09-27 ALAS2KERNEL-5.4-2023-054 Fixed
Amazon Linux 2023 kernel 2023-08-31 ALAS2023-2023-330 Fixed
Amazon Linux 2 - Livepatch Extra kernel-livepatch-4.14.320-243.544 2023-10-31 ALAS2LIVEPATCH-2023-154 Fixed
Amazon Linux 2 - Livepatch Extra kernel-livepatch-5.10.186-179.751 2023-10-31 ALAS2LIVEPATCH-2023-155 Fixed

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H