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High · 7.1 CVE-2024-46828 EUVD-2024-42089GHSA-mrvx-f77x-hmwr

sched: sch_cake: fix bulk flow accounting logic for host fairness

Published Sep 27, 2024 · Updated Aug 5, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.4 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.4 Package: linux-azure-5.8 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-azure-fips Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.4 Package: linux-gcp-5.8 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-5.4 Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-iot Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-5.4 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

sched: sch_cake: fix bulk flow accounting logic for host fairness

In sch_cake, we keep track of the count of active bulk flows per host,
when running in dst/src host fairness mode, which is used as the
round-robin weight when iterating through flows. The count of active
bulk flows is updated whenever a flow changes state.

This has a peculiar interaction with the hash collision handling: when a
hash collision occurs (after the set-associative hashing), the state of
the hash bucket is simply updated to match the new packet that collided,
and if host fairness is enabled, that also means assigning new per-host
state to the flow. For this reason, the bulk flow counters of the
host(s) assigned to the flow are decremented, before new state is
assigned (and the counters, which may not belong to the same host
anymore, are incremented again).

Back when this code was introduced, the host fairness mode was always
enabled, so the decrement was unconditional. When the configuration
flags were introduced the *increment* was made conditional, but
the *decrement* was not. Which of course can lead to a spurious
decrement (and associated wrap-around to U16_MAX).

AFAICT, when host fairness is disabled, the decrement and wrap-around
happens as soon as a hash collision occurs (which is not that common in
itself, due to the set-associative hashing). However, in most cases this
is harmless, as the value is only used when host fairness mode is
enabled. So in order to trigger an array overflow, sch_cake has to first
be configured with host fairness disabled, and while running in this
mode, a hash collision has to occur to cause the overflow. Then, the
qdisc has to be reconfigured to enable host fairness, which leads to the
array out-of-bounds because the wrapped-around value is retained and
used as an array index. It seems that syzbot managed to trigger this,
which is quite impressive in its own right.

This patch fixes the issue by introducing the same conditional check on
decrement as is used on increment.

The original bug predates the upstreaming of cake, but the commit listed
in the Fixes tag touched that code, meaning that this patch won't apply
before that.

Affected products

VendorProductAffectedFixed
Linux Linux 5.1 5.4.284

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 6.10.11-1 —
Debian 13 linux 6.10.11-1 —
Debian 12 linux 6.1.112-1 DSA-5782-1
Debian 11 linux 5.10.226-1 DLA-3912-1
Debian 11 linux-6.1 6.1.119-1~deb11u1 DLA-4008-1
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1056.58 —
Ubuntu 24.04 LTS linux 6.8.0-50.51 USN-7154-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1020.22 USN-7154-1
Ubuntu 24.04 LTS linux-azure 6.8.0-1020.23 USN-7196-1
Ubuntu 24.04 LTS linux-gcp +1 6.8.0-1019.21 USN-7155-1, USN-7154-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1015.19 USN-7154-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1002.4 USN-7156-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1017.17 USN-7154-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1019.21.1 USN-7155-1
Ubuntu 24.04 LTS linux-oem-6.8 6.8.0-1018.18 USN-7154-1
Ubuntu 24.04 LTS linux-oracle +1 6.8.0-1017.18 USN-7154-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1016.18 USN-7154-1
Ubuntu 24.04 LTS linux-riscv +1 6.8.0-50.51.1 USN-7154-1
Ubuntu 22.04 LTS linux +1 5.15.0-125.135 USN-7100-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1072.78 USN-7100-2
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1020.22~22.04.1 USN-7154-1
Ubuntu 22.04 LTS linux-azure 5.15.0-1075.84 USN-7123-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1020.23~22.04.1 USN-7196-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1076.85.1 —
Ubuntu 22.04 LTS linux-gcp 5.15.0-1071.79 USN-7100-1
Ubuntu 22.04 LTS linux-gcp-6.8 +1 6.8.0-1019.21~22.04.1 USN-7155-1, USN-7154-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1069.75 USN-7100-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1055.62 USN-7100-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-50.51~22.04.1 USN-7154-2
Ubuntu 22.04 LTS linux-ibm +1 5.15.0-1065.68 USN-7100-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1017.17~22.04.1 —
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1067.73 USN-7144-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1069.74 USN-7100-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1067.68 USN-7100-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1032.32 —
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1020.20 —
Ubuntu 22.04 LTS linux-oracle 5.15.0-1070.76 USN-7100-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1017.18~22.04.1 USN-7154-1
Ubuntu 22.04 LTS linux-riscv +31 No fix yet —
Ubuntu 22.04 LTS linux-riscv-6.8 +1 6.8.0-50.51.1~22.04.1 USN-7154-1
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1038.42 USN-7100-1
Ubuntu 20.04 LTS linux 5.4.0-200.220 USN-7088-1
Ubuntu 20.04 LTS linux-aws 5.4.0-1135.145 USN-7088-4
Ubuntu 20.04 LTS linux-aws-5.15 5.15.0-1072.78~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-azure 5.4.0-1140.147 USN-7088-2
Ubuntu 20.04 LTS linux-azure-5.15 5.15.0-1078.87~20.04.1 USN-7194-1
Ubuntu 20.04 LTS linux-bluefield 5.4.0-1095.102 USN-7088-2
Ubuntu 20.04 LTS linux-gcp 5.4.0-1139.148 USN-7088-1
Ubuntu 20.04 LTS linux-gcp-5.15 5.15.0-1071.79~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-gke +26 No fix yet —
Ubuntu 20.04 LTS linux-gkeop 5.4.0-1102.106 USN-7088-1
Ubuntu 20.04 LTS linux-gkeop-5.15 5.15.0-1055.62~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-hwe-5.15 +1 5.15.0-125.135~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-ibm 5.4.0-1082.87 USN-7088-1
Ubuntu 20.04 LTS linux-ibm-5.15 5.15.0-1065.68~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-intel-iotg-5.15 5.15.0-1067.73~20.04.1 USN-7144-1
Ubuntu 20.04 LTS linux-iot 5.4.0-1044.45 USN-7119-1
Ubuntu 20.04 LTS linux-kvm 5.4.0-1123.131 USN-7088-4
Ubuntu 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1032.32~20.04.1 —
Ubuntu 20.04 LTS linux-oracle 5.4.0-1134.143 USN-7088-4
Ubuntu 20.04 LTS linux-oracle-5.15 5.15.0-1070.76~20.04.1 USN-7100-1
Ubuntu 20.04 LTS linux-raspi 5.4.0-1119.131 USN-7088-5
Ubuntu 20.04 LTS linux-riscv-5.15 5.15.0-1068.72~20.04.1 —
Ubuntu 20.04 LTS linux-xilinx-zynqmp 5.4.0-1054.58 USN-7088-4
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Show 9 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2015.16 —
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1013.14 —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1066.68 —
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1073.81 —
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1013.14~22.04.1 —
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-78.78+fips1 —
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1072.78+fips1 —
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1075.84+fips1 —
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-125.135+fips1 —
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1071.79+fips1 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-aws-fips 5.4.0-1135.145+fips1 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-azure-fips 5.4.0-1140.147+fips1 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips 5.4.0-1109.119 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-gcp-fips 5.4.0-1139.148+fips1 —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 18.04 LTS linux-aws-5.4 5.4.0-1135.145~18.04.1 USN-7088-3
Ubuntu Pro 18.04 LTS linux-azure-5.4 5.4.0-1140.147~18.04.1 USN-7088-4
Ubuntu Pro 18.04 LTS linux-gcp-5.4 5.4.0-1139.148~18.04.1 USN-7088-1
Ubuntu Pro 18.04 LTS linux-hwe-5.4 5.4.0-200.220~18.04.1 USN-7088-1
Ubuntu Pro 18.04 LTS linux-ibm-5.4 5.4.0-1082.87~18.04.1 USN-7088-1
Ubuntu Pro 18.04 LTS linux-oracle-5.4 5.4.0-1134.143~18.04.1 USN-7088-3
Ubuntu Pro 18.04 LTS linux-raspi-5.4 5.4.0-1119.131~18.04.1 USN-7088-5
ReleasePackageFixed inAdvisory
RHEL 9 rv +77 5.14.0-570.12.1.el9_6 RHSA-2025:6966
ReleasePackageFixed inAdvisory
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.30.1 SUSE-SU-2024:4318-1
SLES 15 SP6 kernel-azure 6.4.0-150600.8.17.2 SUSE-SU-2024:4316-1, SUSE-SU-2024:3984-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.9.coco15sp6.1 SUSE-SU-2024:4387-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.30.1.150600.12.12.6 SUSE-SU-2024:4318-1
SLES 15 SP6 kernel-syms-azure +1 6.4.0-150600.8.17.1 SUSE-SU-2024:4316-1, SUSE-SU-2024:3984-1
SLES 15 SP5 kernel-64kb +6 5.14.21-150500.55.88.1 SUSE-SU-2024:4364-1
SLES 15 SP5 kernel-azure +2 5.14.21-150500.33.72.1 SUSE-SU-2024:3983-1
SLES 15 SP5 kernel-default-base 5.14.21-150500.55.88.1.150500.6.39.4 SUSE-SU-2024:4364-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLE Micro 6.1 kernel-default-base 6.4.0-24.1.21.4 SUSE-SU-2025:20247-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0-RT_Update_4 1-1.1 SUSE-SU-2025:20246-1
SLE Micro 6.1 kernel-livepatch-MICRO-6-0_Update_4 1-1.2 SUSE-SU-2025:20247-1
SLE Micro 6.1 kernel-rt +1 6.4.0-22.1 SUSE-SU-2025:20246-1
SLE Micro 6.1 kernel-source +2 6.4.0-24.1 SUSE-SU-2025:20247-1
SLE Micro 6.0 kernel-default-base 6.4.0-24.1.21.4 SUSE-SU-2025:20164-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0-RT_Update_4 1-1.1 SUSE-SU-2025:20163-1
SLE Micro 6.0 kernel-livepatch-MICRO-6-0_Update_4 1-1.2 SUSE-SU-2025:20164-1
SLE Micro 6.0 kernel-rt +1 6.4.0-22.1 SUSE-SU-2025:20163-1
SLE Micro 6.0 kernel-source +2 6.4.0-24.1 SUSE-SU-2025:20164-1
SLE Micro 5.5 kernel-default 5.14.21-150500.55.88.1 SUSE-SU-2024:4364-1
SLE Micro 5.5 kernel-default-base 5.14.21-150500.55.88.1.150500.6.39.4 SUSE-SU-2024:4364-1
SLE Micro 5.5 kernel-rt +1 5.14.21-150500.13.76.1 SUSE-SU-2024:3985-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.30.1 SUSE-SU-2024:4318-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_5 +1 1-150600.1.3.1 SUSE-SU-2024:4314-1, SUSE-SU-2024:3986-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_6 1-150600.13.3.5 SUSE-SU-2024:4318-1
SLE Live Patching 15 SP5 kernel-default 5.14.21-150500.55.88.1 SUSE-SU-2024:4364-1
SLE Live Patching 15 SP5 kernel-livepatch-SLE15-SP5-RT_Update_22 1-150500.11.3.1 SUSE-SU-2024:3985-1
SLE Live Patching 15 SP5 kernel-livepatch-SLE15-SP5_Update_21 1-150500.11.5.1 SUSE-SU-2024:4364-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.17.1 SUSE-SU-2024:4314-1, SUSE-SU-2024:3986-1
SUSE Real Time Module 15 SP5 kernel-rt +3 5.14.21-150500.13.76.1 SUSE-SU-2024:3985-1
ReleasePackageFixed inAdvisory
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.30.1 SUSE-SU-2024:4318-1
openSUSE Leap 15.6 kernel-azure 6.4.0-150600.8.17.2 SUSE-SU-2024:4316-1, SUSE-SU-2024:3984-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.30.1.150600.12.12.6 SUSE-SU-2024:4318-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.17.1 SUSE-SU-2024:4314-1, SUSE-SU-2024:3986-1
openSUSE Leap 15.6 kernel-syms-azure +1 6.4.0-150600.8.17.1 SUSE-SU-2024:4316-1, SUSE-SU-2024:3984-1
openSUSE Leap 15.5 kernel-azure +2 5.14.21-150500.33.72.1 SUSE-SU-2024:3983-1
openSUSE Leap 15.5 kernel-rt +3 5.14.21-150500.13.76.1 SUSE-SU-2024:3985-1
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
openSUSE Leap Micro 5.5 kernel-rt 5.14.21-150500.13.76.1 SUSE-SU-2024:3985-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.1.111-120.187 1.0-0.amzn2023 ALAS2023-2024-744
Amazon Linux 2023 perf +14 6.1.111-120.187.amzn2023 ALAS2023-2024-744

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 bpftool 7.5.0-802.el9_6 ELSA-2025-6966
Oracle Linux 9 rv +28 5.14.0-570.12.1.0.1.el9_6 ELSA-2025-6966
Oracle Linux 8 bpftool +13 5.15.0-302.167.6.el9uek ELSA-2024-12815
Oracle Linux 7 kernel-uek +6 5.4.17-2136.337.5.el8uek ELSA-2024-12813
Oracle Linux 7 perf +3 5.4.17-2136.337.5.el7uek ELSA-2024-12813

Advisories 40

References