Описание
In the Linux kernel, the following vulnerability has been resolved:
net: bridge: use option bits for CFM/MRP frame handlers
CFM and MRP register a global br_frame_type whose hlist_node is linked
into the per-bridge frame_type_list when the first MEP/MRP instance is
created. Enabling the protocol on multiple bridges therefore inserts the
same node into multiple lists. Unregistering it on one bridge then
corrupts list state belonging to another.
These handlers can only be installed once per bridge, and they are
uncommon. Track their per-bridge enable state with net_bridge option
bits, which already live on the Rx hot cache line, and dispatch the
matching handler directly from the receive path. Check both bits
together first as an unlikely case.
Remove the generic frame_type_list and br_frame_type helpers, which
have had no other users since CFM and MRP were added. That shrinks
struct net_bridge by 8 bytes and drops the list walk from the fast
path. When neither protocol is compiled in, BR_CFM_MRP_OPTS is 0 and
the compiler prunes the branch.
A flaw was found in the Linux kernel's network bridge subsystem, which can lead to a Denial of Service (DoS) due to list corruption. When Connectivity Fault Management (CFM) or Media Redundancy Protocol (MRP) handlers are enabled across multiple network bridges, a shared data structure is improperly linked into multiple bridge lists. A local privileged user unregistering the protocol on one bridge can corrupt the active state of another bridge, resulting in a kernel crash.
Отчет
A low impact vulnerability was found in the Linux kernel's network bridge subsystem. When Connectivity Fault Management (CFM) or Media Redundancy Protocol (MRP) is enabled on multiple bridge devices, a shared frame-handler data structure is linked into each bridge's frame handler list. Unregistering the protocol on one bridge then corrupts the list state belonging to another bridge, which can result in a kernel crash and a local denial of service. Exploiting this flaw requires local access with the privileges needed to configure network bridges (CAP_NET_ADMIN), and it affects availability only, with no impact on confidentiality or integrity. The kernel packages in Red Hat Enterprise Linux 8, 9, and 10 (including kernel-rt), RHIVOS 2, and the RHEL CoreOS kernels shipped with OpenShift 4 are affected, with the fix deferred to a future update: the upstream solution reworks the bridge frame-handler registration mechanism (replacing the shared handler list with per-bridge option bits) rather than applying a minimal change, and the flaw's low security impact does not justify an expedited update. The residual risk is a local denial of service limited to systems where the uncommon CFM or MRP protocols are enabled across multiple bridge devices. Red Hat Enterprise Linux 7 (kernel and kernel-rt) and Red Hat Enterprise Linux 8.4 are not affected because the vulnerable code is not present in those streams. Although the CVSS:3.1 base score is 5.5 (Moderate), Red Hat rates the impact of this flaw as Low because exploitation requires local privileged access and only availability is affected.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Fix deferred |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: net: bridge: use option bits for CFM/MRP frame handlers CFM and MRP register a global br_frame_type whose hlist_node is linked into the per-bridge frame_type_list when the first MEP/MRP instance is created. Enabling the protocol on multiple bridges therefore inserts the same node into multiple lists. Unregistering it on one bridge then corrupts list state belonging to another. These handlers can only be installed once per bridge, and they are uncommon. Track their per-bridge enable state with net_bridge option bits, which already live on the Rx hot cache line, and dispatch the matching handler directly from the receive path. Check both bits together first as an unlikely case. Remove the generic frame_type_list and br_frame_type helpers, which have had no other users since CFM and MRP were added. That shrinks struct net_bridge by 8 bytes and drops the list walk from the fast path. When neither protocol is compiled in...
In the Linux kernel, the following vulnerability has been resolved: net: bridge: use option bits for CFM/MRP frame handlers CFM and MRP register a global br_frame_type whose hlist_node is linked into the per-bridge frame_type_list when the first MEP/MRP instance is created. Enabling the protocol on multiple bridges therefore inserts the same node into multiple lists. Unregistering it on one bridge then corrupts list state belonging to another. These handlers can only be installed once per bridge, and they are uncommon. Track their per-bridge enable state with net_bridge option bits, which already live on the Rx hot cache line, and dispatch the matching handler directly from the receive path. Check both bits together first as an unlikely case. Remove the generic frame_type_list and br_frame_type helpers, which have had no other users since CFM and MRP were added. That shrinks struct net_bridge by 8 bytes and drops the list walk from the fast path. When neither protocol is compiled i
net: bridge: use option bits for CFM/MRP frame handlers
In the Linux kernel, the following vulnerability has been resolved: n ...
In the Linux kernel, the following vulnerability has been resolved: net: bridge: use option bits for CFM/MRP frame handlers CFM and MRP register a global br_frame_type whose hlist_node is linked into the per-bridge frame_type_list when the first MEP/MRP instance is created. Enabling the protocol on multiple bridges therefore inserts the same node into multiple lists. Unregistering it on one bridge then corrupts list state belonging to another. These handlers can only be installed once per bridge, and they are uncommon. Track their per-bridge enable state with net_bridge option bits, which already live on the Rx hot cache line, and dispatch the matching handler directly from the receive path. Check both bits together first as an unlikely case. Remove the generic frame_type_list and br_frame_type helpers, which have had no other users since CFM and MRP were added. That shrinks struct net_bridge by 8 bytes and drops the list walk from the fast path. When neither protocol is compile...
EPSS
5.5 Medium
CVSS3