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Unscored CVE-2021-47321 EUVD-2021-34326GHSA-fhjr-hghh-2jv9

watchdog: Fix possible use-after-free by calling del_timer_sync()

Published May 21, 2024 · Updated May 11, 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-5.19 Package: linux-aws-5.3 Package: linux-aws-5.4 Package: linux-aws-5.8 Package: linux-aws-6.2 Package: linux-aws-fips Package: linux-aws-hwe Package: linux-azure Package: linux-azure-4.15 Package: linux-azure-5.11 Package: linux-azure-5.13 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-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-4.15 Package: linux-gcp-5.11 Package: linux-gcp-5.13 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-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-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.19 Package: linux-hwe-5.4 Package: linux-hwe-5.8 Package: linux-hwe-6.2 Package: linux-hwe-edge Package: linux-ibm Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-kvm Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.2 Package: linux-lts-xenial Package: linux-nvidia-6.2 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-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.4 Package: linux-oracle-5.8 Package: linux-raspi Package: linux-raspi-5.4 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-starfive-5.19 Package: linux-starfive-6.2 Package: linux-vmware Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

watchdog: Fix possible use-after-free by calling del_timer_sync()

This driver's remove path calls del_timer(). However, that function
does not wait until the timer handler finishes. This means that the
timer handler may still be running after the driver's remove function
has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler
has finished, and unable to re-schedule itself.

Affected products

VendorProductAffectedFixed
Linux Linux 4.3 4.4.276

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 5.14.6-1 —
Debian 13 linux 5.14.6-1 —
Debian 12 linux 5.14.6-1 —
ReleasePackageFixed inAdvisory
Ubuntu 24.04 LTS linux-raspi-realtime No fix yet —
Ubuntu 22.04 LTS linux-riscv +22 No fix yet —
Ubuntu 20.04 LTS linux 5.4.0-88.99 —
Ubuntu 20.04 LTS linux-aws 5.4.0-1057.60 —
Ubuntu 20.04 LTS linux-azure 5.4.0-1059.62 —
Ubuntu 20.04 LTS linux-bluefield 5.4.0-1019.22 —
Ubuntu 20.04 LTS linux-gcp 5.4.0-1053.57 —
Ubuntu 20.04 LTS linux-gke +26 No fix yet —
Ubuntu 20.04 LTS linux-gkeop 5.4.0-1024.25 —
Ubuntu 20.04 LTS linux-ibm 5.4.0-1005.6 —
Ubuntu 20.04 LTS linux-kvm 5.4.0-1047.49 —
Ubuntu 20.04 LTS linux-oracle 5.4.0-1055.59 —
Ubuntu 20.04 LTS linux-raspi 5.4.0-1044.48 —
Ubuntu 18.04 LTS linux 4.15.0-156.163 —
Ubuntu 18.04 LTS linux-aws 4.15.0-1111.118 —
Ubuntu 18.04 LTS linux-aws-5.4 5.4.0-1057.60~18.04.1 —
Ubuntu 18.04 LTS linux-azure-4.15 4.15.0-1123.136 —
Ubuntu 18.04 LTS linux-azure-5.4 5.4.0-1059.62~18.04.1 —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 18.04 LTS linux-gcp-4.15 4.15.0-1108.122 —
Ubuntu 18.04 LTS linux-gcp-5.4 5.4.0-1053.57~18.04.1 —
Ubuntu 18.04 LTS linux-hwe-5.4 5.4.0-87.98~18.04.1 —
Ubuntu 18.04 LTS linux-kvm 4.15.0-1099.101 —
Ubuntu 18.04 LTS linux-oracle 4.15.0-1080.88 —
Ubuntu 18.04 LTS linux-oracle-5.4 5.4.0-1055.59~18.04.1 —
Ubuntu 18.04 LTS linux-raspi-5.4 5.4.0-1044.48~18.04.1 —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Show 8 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 16.04 LTS linux-fips No fix yet —
Ubuntu Pro FIPS-updates 20.04 LTS linux-aws-fips 5.4.0-1069.73+fips2 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-azure-fips 5.4.0-1073.76+fips1 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips 5.4.0-1034.40 —
Ubuntu Pro FIPS-updates 20.04 LTS linux-gcp-fips 5.4.0-1067.71~20.04.1 —
Ubuntu Pro FIPS-updates 18.04 LTS linux-aws-fips 4.15.0-2053.55 —
Ubuntu Pro FIPS-updates 18.04 LTS linux-azure-fips 4.15.0-2035.39 —
Ubuntu Pro FIPS-updates 18.04 LTS linux-fips 4.15.0-1069.78 —
Ubuntu Pro FIPS-updates 18.04 LTS linux-gcp-fips 4.15.0-2018.20 —
Ubuntu Pro FIPS-updates 16.04 LTS linux-fips No fix yet —
Ubuntu Pro 16.04 LTS linux +2 No fix yet —
Ubuntu Pro 16.04 LTS linux-aws-hwe 4.15.0-1111.118~16.04.1 —
Ubuntu Pro 16.04 LTS linux-azure 4.15.0-1123.136~16.04.1 —
Ubuntu Pro 16.04 LTS linux-gcp 4.15.0-1108.122~16.04.1 —
Ubuntu Pro 16.04 LTS linux-hwe 4.15.0-156.163~16.04.1 —
Ubuntu Pro 16.04 LTS linux-oracle 4.15.0-1080.88~16.04.1 —
Ubuntu Pro 14.04 LTS linux-aws +1 No fix yet —
Ubuntu Pro 14.04 LTS linux-azure 4.15.0-1123.136~14.04.1 —
ReleasePackageFixed inAdvisory
RHEL 8 kernel-rt +12 4.18.0-553.22.1.rt7.363.el8_10 RHSA-2024:7001
RHEL 8 perf +26 4.18.0-553.22.1.el8_10 RHSA-2024:7000
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
RHEL 8.8 EUS perf +26 4.18.0-477.75.1.el8_8 RHSA-2024:8107

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 8 kernel-rt +11 4.18.0-553.22.1.rt7.363.el8_10 ALSA-2024:7001
AlmaLinux 8 perf +24 4.18.0-553.22.1.el8_10 ALSA-2024:7000

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 8 kernel 4.18.0-553.22.1.el8_10 RLSA-2024:7000
Rocky Linux 8 kernel-rt 4.18.0-553.22.1.rt7.363.el8_10 RLSA-2024:7001
ReleasePackageFixed inAdvisory
SLES 15 SP3 kernel-64kb +7 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLES 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLES 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLES 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SLES 12 SP5 kernel-azure +2 4.12.14-16.188.1 SUSE-SU-2024:1979-1
SLES 12 SP5 kernel-docs +4 4.12.14-122.219.1 SUSE-SU-2024:2184-1
SLES 11 SP4 kernel-ec2 +5 3.0.101-108.156.1 SUSE-SU-2024:1978-1
Show 12 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLES for SAP 15 SP3 kernel-docs +5 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLES for SAP 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLES for SAP 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SLES for SAP 12 SP5 kernel-azure +2 4.12.14-16.188.1 SUSE-SU-2024:1979-1
SLES for SAP 12 SP5 kernel-syms +2 4.12.14-122.219.1 SUSE-SU-2024:2184-1
SLE Real Time 12 SP5 kernel-rt +3 4.12.14-10.188.1 SUSE-SU-2024:1983-1
SLE Micro 5.2 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Micro 5.2 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE Micro 5.2 kernel-rt +1 5.3.18-150300.172.1 SUSE-SU-2024:2010-1
SLE Micro 5.1 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Micro 5.1 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE Micro 5.1 kernel-rt +1 5.3.18-150300.172.1 SUSE-SU-2024:2010-1
SLE Live Patching 15 SP3 kernel-default 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE Live Patching 15 SP3 kernel-livepatch-SLE15-SP3_Update_45 1-150300.7.3.1 SUSE-SU-2024:2185-1
SLE Live Patching 15 SP2 kernel-default 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SLE Live Patching 15 SP2 kernel-livepatch-SLE15-SP2_Update_49 1-150200.5.3.1 SUSE-SU-2024:2183-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.219.1 SUSE-SU-2024:2184-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_57 1-8.3.1 SUSE-SU-2024:2184-1
SLE HPC 15 SP3 kernel-64kb +6 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SLE HPC 15 SP3 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1
SLE HPC 15 SP2 kernel-default-base 5.3.18-150200.24.194.1.150200.9.99.1 SUSE-SU-2024:2183-1
SLE HPC 15 SP2 kernel-docs +5 5.3.18-150200.24.194.1 SUSE-SU-2024:2183-1
SUSE Enterprise Storage 7.1 kernel-64kb +6 5.3.18-150300.59.164.1 SUSE-SU-2024:2185-1
SUSE Enterprise Storage 7.1 kernel-default-base 5.3.18-150300.59.164.1.150300.18.96.1 SUSE-SU-2024:2185-1

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 8 perf +19 4.18.0-553.22.1.el8_10 ELSA-2024-7000

Advisories 15

References