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Unscored CVE-2025-37953 EUVD-2025-15902GHSA-ccmh-pfgg-525g

sch_htb: make htb_deactivate() idempotent

Published May 20, 2025 · Updated May 11, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.2 Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.2 Package: linux-gcp-6.5 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-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-edge Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 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-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.5 Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.5 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

sch_htb: make htb_deactivate() idempotent

Alan reported a NULL pointer dereference in htb_next_rb_node()
after we made htb_qlen_notify() idempotent.

It turns out in the following case it introduced some regression:

htb_dequeue_tree():
|-> fq_codel_dequeue()
|-> qdisc_tree_reduce_backlog()
|-> htb_qlen_notify()
|-> htb_deactivate()
|-> htb_next_rb_node()
|-> htb_deactivate()

For htb_next_rb_node(), after calling the 1st htb_deactivate(), the
clprio[prio]->ptr could be already set to NULL, which means
htb_next_rb_node() is vulnerable here.

For htb_deactivate(), although we checked qlen before calling it, in
case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again
which triggers the warning inside.

To fix the issues here, we need to:

1) Make htb_deactivate() idempotent, that is, simply return if we
already call it before.
2) Make htb_next_rb_node() safe against ptr==NULL.

Many thanks to Alan for testing and for the reproducer.

Affected products

VendorProductAffectedFixed
Linux Linux 6.1.138 – < 6.1.139, 6.6.90 – < 6.6.91, 6.12.28 – < 6.12.29, 6.14.6 – < 6.14.7 6.1.139

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.

Debian

Security tracker ↗
ReleasePackageFixed inAdvisory
Debian 14 linux 6.12.29-1 —
Debian 13 linux 6.12.29-1 —
Debian 12 linux 6.1.140-1 DSA-5925-1
Debian 11 linux-6.1 6.1.140-1~deb11u1 DLA-4271-1

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS linux-realtime +1 No fix yet —
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —

SUSE

Security tracker ↗
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +6 6.4.0-150700.53.6.1 SUSE-SU-2025:02307-1
SLES 15 SP7 kernel-azure +2 6.4.0-150700.20.6.1 SUSE-SU-2025:02254-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.6.1.150700.17.6.1 SUSE-SU-2025:02307-1
SLES 15 SP6 kernel-64kb +6 6.4.0-150600.23.53.1 SUSE-SU-2025:02000-1
SLES 15 SP6 kernel-azure +2 6.4.0-150600.8.40.1 SUSE-SU-2025:01965-1
SLES 15 SP6 kernel-coco +3 6.4.0-15061.28.coco15sp6.1 SUSE-SU-2025:02923-1
SLES 15 SP6 kernel-default-base 6.4.0-150600.23.53.1.150600.12.24.1 SUSE-SU-2025:02000-1
SLES 15 SP5 kernel-64kb +6 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLES 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLES 15 SP4 kernel-64kb +3 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLES 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLES 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SLES 15 SP3 kernel-64kb +6 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLES 15 SP3 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLES 15 SP3 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1
Show 23 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES 12 SP5 kernel-syms +2 4.12.14-122.261.1 SUSE-SU-2025:01983-1
SLES for SAP 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLES for SAP 15 SP5 kernel-docs +4 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLES for SAP 15 SP4 kernel-default +1 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLES for SAP 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLES for SAP 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SLES for SAP 15 SP3 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLES for SAP 15 SP3 kernel-docs +4 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLES for SAP 15 SP3 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1
SLE Micro 6.1 kernel-default-base 6.4.0-30.1.21.8 SUSE-SU-2025:20419-1
SLE Micro 6.1 kernel-rt +1 6.4.0-33.1 SUSE-SU-2025:20421-1
SLE Micro 6.1 kernel-source +2 6.4.0-30.1 SUSE-SU-2025:20419-1
SLE Micro 6.0 kernel-default-base 6.4.0-30.1.21.8 SUSE-SU-2025:20408-1
SLE Micro 6.0 kernel-rt +1 6.4.0-33.1 SUSE-SU-2025:20413-1
SLE Micro 6.0 kernel-source +2 6.4.0-30.1 SUSE-SU-2025:20408-1
SLE Micro 5.5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLE Micro 5.5 kernel-rt 5.14.21-150500.13.100.2 SUSE-SU-2025:02321-1
SLE Micro 5.5 kernel-source +1 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE Micro 5.5 kernel-source-rt 5.14.21-150500.13.100.1 SUSE-SU-2025:02321-1
SLE Micro 5.4 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE Micro 5.4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE Micro 5.4 kernel-rt +1 5.14.21-150400.15.124.1 SUSE-SU-2025:02322-1
SLE Micro 5.3 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE Micro 5.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE Micro 5.3 kernel-rt +1 5.14.21-150400.15.124.1 SUSE-SU-2025:02322-1
SLE Micro 5.2 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Micro 5.2 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLE Micro 5.2 kernel-rt +1 5.3.18-150300.214.1 SUSE-SU-2025:02320-1
SLE Micro 5.1 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Micro 5.1 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SLE Micro 5.1 kernel-rt +1 5.3.18-150300.214.1 SUSE-SU-2025:02320-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.6.1 SUSE-SU-2025:02307-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_2 1-150700.1.5.1 SUSE-SU-2025:02333-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_2 1-150700.15.3.1 SUSE-SU-2025:02307-1
SLE Live Patching 15 SP6 kernel-default 6.4.0-150600.23.53.1 SUSE-SU-2025:02000-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6-RT_Update_11 1-150600.1.3.2 SUSE-SU-2025:01964-1
SLE Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_12 1-150600.13.3.1 SUSE-SU-2025:02000-1
SLE Live Patching 15 SP5 kernel-default 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE Live Patching 15 SP5 kernel-livepatch-SLE15-SP5_Update_28 1-150500.11.3.1 SUSE-SU-2025:02264-1
SLE Live Patching 15 SP3 kernel-default 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SLE Live Patching 15 SP3 kernel-livepatch-SLE15-SP3_Update_59 1-150300.7.3.1 SUSE-SU-2025:02308-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.261.1 SUSE-SU-2025:01983-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_69 1-8.3.1 SUSE-SU-2025:01983-1
SLE HPC 15 SP5 kernel-64kb +5 5.14.21-150500.55.113.1 SUSE-SU-2025:02264-1
SLE HPC 15 SP5 kernel-default-base 5.14.21-150500.55.113.1.150500.6.53.1 SUSE-SU-2025:02264-1
SLE HPC 15 SP4 kernel-64kb +2 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SLE HPC 15 SP4 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SLE HPC 15 SP4 kernel-docs +2 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.8.1 SUSE-SU-2025:02333-1
SUSE Real Time Module 15 SP6 kernel-rt +3 6.4.0-150600.10.39.1 SUSE-SU-2025:01964-1
SUSE Manager Server 4.3 kernel-default +1 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SUSE Manager Server 4.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SUSE Manager Server 4.3 kernel-syms +1 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-default 5.14.21-150400.24.170.2 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-default-base 5.14.21-150400.24.170.2.150400.24.86.2 SUSE-SU-2025:02537-1
SUSE Manager Proxy 4.3 kernel-syms +1 5.14.21-150400.24.170.1 SUSE-SU-2025:02537-1
SUSE Enterprise Storage 7.1 kernel-64kb +5 5.3.18-150300.59.211.1 SUSE-SU-2025:02308-1
SUSE Enterprise Storage 7.1 kernel-default-base 5.3.18-150300.59.211.1.150300.18.126.1 SUSE-SU-2025:02308-1
SUSE Enterprise Storage 7.1 kernel-obs-build 5.3.18-150300.59.212.1 SUSE-SU-2025:02308-1

openSUSE

Security tracker ↗
ReleasePackageFixed inAdvisory
openSUSE Leap 15.6 dtb-aarch64 +10 6.4.0-150600.23.53.1 SUSE-SU-2025:02000-1
openSUSE Leap 15.6 kernel-azure +2 6.4.0-150600.8.40.1 SUSE-SU-2025:01965-1
openSUSE Leap 15.6 kernel-default-base 6.4.0-150600.23.53.1.150600.12.24.1 SUSE-SU-2025:02000-1
openSUSE Leap 15.6 kernel-rt +3 6.4.0-150600.10.39.1 SUSE-SU-2025:01964-1

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-101.33.4.3.el10uek ELSA-2025-20530, ELSA-2025-20480
Oracle Linux 8 bpftool +18 5.15.0-314.193.5.3.el9uek ELSA-2025-25757
Oracle Linux 7 kernel-uek +6 5.4.17-2136.346.6.el8uek ELSA-2025-20521
Oracle Linux 7 kernel-uek-tools 5.4.17-2136.346.6.el7uek ELSA-2025-20521

Advisories 25

References