Описание
A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation.
When fw_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 76e42ae831991c828cffa8c37736ebfb831ad5ec.
There are 3 CVEs for the use-after-free flaw found in net/sched/cls_fw.c in classifiers (cls_fw, cls_u32, and cls_route) in the Linux Kernel: CVE-2023-4206, CVE-2023-4207, CVE-2023-4208.
A local user could use any of these flaws to crash the system or potentially escalate their privileges on the system.
Similar CVE-2023-4128 was rejected as a duplicate.
Меры по смягчению последствий
To mitigate this issue, prevent the module cls_u32 from being loaded by blacklisting the module to prevent it from loading automatically.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Fixed | RHSA-2023:7424 | 21.11.2023 |
| Red Hat Enterprise Linux 7 | kpatch-patch | Fixed | RHSA-2023:7419 | 21.11.2023 |
| Red Hat Enterprise Linux 7 | kernel | Fixed | RHSA-2023:7423 | 21.11.2023 |
| Red Hat Enterprise Linux 7.6 Advanced Update Support(Disable again in 2026 - SPRHEL-7118) | kernel | Fixed | RHSA-2024:0261 | 16.01.2024 |
| Red Hat Enterprise Linux 7.7 Advanced Update Support | kernel | Fixed | RHSA-2024:0262 | 16.01.2024 |
| Red Hat Enterprise Linux 8 | kernel-rt | Fixed | RHSA-2023:6901 | 14.11.2023 |
| Red Hat Enterprise Linux 8 | kernel | Fixed | RHSA-2023:7077 | 14.11.2023 |
| Red Hat Enterprise Linux 8.8 Extended Update Support | kernel | Fixed | RHSA-2023:7539 | 28.11.2023 |
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Дополнительная информация
Статус:
7.8 High
CVSS3
Связанные уязвимости
A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation. When fw_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 76e42ae831991c828cffa8c37736ebfb831ad5ec.
A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation. When fw_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 76e42ae831991c828cffa8c37736ebfb831ad5ec.
A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw ...
A use-after-free vulnerability in the Linux kernel's net/sched: cls_fw component can be exploited to achieve local privilege escalation. When fw_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 76e42ae831991c828cffa8c37736ebfb831ad5ec.
7.8 High
CVSS3