CVE-2021-47324: watchdog: Fix possible use-after-free in wdt_startup()

Published May 21, 2024
·
Updated

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

watchdog: Fix possible use-after-free in wdtstartup()

This module's remove path calls deltimer(). 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 deltimersync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Affected Software

128 affected componentsFixes available
Linux Kernel
Linux Linux kernel<4.4.276
Linux Linux kernel>=4.5<4.9.276
Linux Linux kernel>=4.10<4.14.240
Linux Linux kernel>=4.15<4.19.198
Linux Linux kernel>=4.20<5.4.134
Linux Linux kernel>=5.5<5.10.52
Linux Linux kernel>=5.11<5.12.19
Linux Linux kernel>=5.13<5.13.4
ubuntu/linux-azure<4.15.0-1123.136~14.04.1
4.15.0-1123.136~14.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-lts-xenial*
ubuntu/linux-aws-hwe<4.15.0-1111.118~16.04.1
4.15.0-1111.118~16.04.1
ubuntu/linux-azure<4.15.0-1123.136~16.04.1
4.15.0-1123.136~16.04.1
ubuntu/linux-gcp<4.15.0-1108.122~16.04.1
4.15.0-1108.122~16.04.1
ubuntu/linux-hwe<4.15.0-156.163~16.04.1
4.15.0-156.163~16.04.1
ubuntu/linux-oracle<4.15.0-1080.88~16.04.1
4.15.0-1080.88~16.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux<4.15.0-156.163
4.15.0-156.163
ubuntu/linux-aws<4.15.0-1111.118
4.15.0-1111.118
ubuntu/linux-aws-5.4<5.4.0-1057.60~18.04.1
5.4.0-1057.60~18.04.1
ubuntu/linux-azure-4.15<4.15.0-1123.136
4.15.0-1123.136
ubuntu/linux-azure-5.4<5.4.0-1059.62~18.04.1
5.4.0-1059.62~18.04.1
ubuntu/linux-gcp-4.15<4.15.0-1108.122
4.15.0-1108.122
ubuntu/linux-gcp-5.4<5.4.0-1053.57~18.04.1
5.4.0-1053.57~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-87.98~18.04.1
5.4.0-87.98~18.04.1
ubuntu/linux-kvm<4.15.0-1099.101
4.15.0-1099.101
ubuntu/linux-oracle<4.15.0-1080.88
4.15.0-1080.88
ubuntu/linux-oracle-5.4<5.4.0-1055.59~18.04.1
5.4.0-1055.59~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1044.48~18.04.1
5.4.0-1044.48~18.04.1
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-fips<4.15.0-2053.55
4.15.0-2053.55
ubuntu/linux-azure-fips<4.15.0-2035.39
4.15.0-2035.39
ubuntu/linux-fips<4.15.0-1069.78
4.15.0-1069.78
ubuntu/linux-gcp-fips<4.15.0-2018.20
4.15.0-2018.20
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-88.99
5.4.0-88.99
ubuntu/linux-aws<5.4.0-1057.60
5.4.0-1057.60
ubuntu/linux-azure<5.4.0-1059.62
5.4.0-1059.62
ubuntu/linux-bluefield<5.4.0-1019.22
5.4.0-1019.22
ubuntu/linux-gcp<5.4.0-1053.57
5.4.0-1053.57
ubuntu/linux-gkeop<5.4.0-1024.25
5.4.0-1024.25
ubuntu/linux-ibm<5.4.0-1005.6
5.4.0-1005.6
ubuntu/linux-kvm<5.4.0-1047.49
5.4.0-1047.49
ubuntu/linux-oracle<5.4.0-1055.59
5.4.0-1055.59
ubuntu/linux-raspi<5.4.0-1044.48
5.4.0-1044.48
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.8*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.8*
ubuntu/linux-intel-5.13*
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.8*
ubuntu/linux-aws-fips<5.4.0-1069.73+fips2
5.4.0-1069.73+fips2
ubuntu/linux-azure-fips<5.4.0-1073.76+fips1
5.4.0-1073.76+fips1
ubuntu/linux-fips<5.4.0-1034.40
5.4.0-1034.40
ubuntu/linux-gcp-fips<5.4.0-1067.71~20.04.1
5.4.0-1067.71~20.04.1
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-nvidia-6.2*
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-raspi-realtime*
ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 4.15.0-1123.136~14.04.1
  2. Upgrade

    Upgrade ubuntu/linux-aws-hwe to a version that resolves this vulnerability.

    Fixed in 4.15.0-1111.118~16.04.1
  3. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 4.15.0-1123.136~16.04.1
  4. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 4.15.0-1108.122~16.04.1
  5. Upgrade

    Upgrade ubuntu/linux-hwe to a version that resolves this vulnerability.

    Fixed in 4.15.0-156.163~16.04.1
  6. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 4.15.0-1080.88~16.04.1
  7. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 4.15.0-156.163
  8. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 4.15.0-1111.118
  9. Upgrade

    Upgrade ubuntu/linux-aws-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1057.60~18.04.1
  10. Upgrade

    Upgrade ubuntu/linux-azure-4.15 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1123.136
  11. Upgrade

    Upgrade ubuntu/linux-azure-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1059.62~18.04.1
  12. Upgrade

    Upgrade ubuntu/linux-gcp-4.15 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1108.122
  13. Upgrade

    Upgrade ubuntu/linux-gcp-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1053.57~18.04.1
  14. Upgrade

    Upgrade ubuntu/linux-hwe-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-87.98~18.04.1
  15. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 4.15.0-1099.101
  16. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 4.15.0-1080.88
  17. Upgrade

    Upgrade ubuntu/linux-oracle-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1055.59~18.04.1
  18. Upgrade

    Upgrade ubuntu/linux-raspi-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1044.48~18.04.1
  19. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-2053.55
  20. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-2035.39
  21. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-1069.78
  22. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 4.15.0-2018.20
  23. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 5.4.0-88.99
  24. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 5.4.0-1057.60
  25. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 5.4.0-1059.62
  26. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 5.4.0-1019.22
  27. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.4.0-1053.57
  28. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 5.4.0-1024.25
  29. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 5.4.0-1005.6
  30. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.4.0-1047.49
  31. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.4.0-1055.59
  32. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 5.4.0-1044.48
  33. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1069.73+fips2
  34. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1073.76+fips1
  35. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1034.40
  36. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1067.71~20.04.1
  37. Configuration

    Replace del_timer() with del_timer_sync() in the module's remove path so the timer handler has finished and cannot reschedule itself before removal completes.

    Linux kernel watchdog wdt_startup() remove path timer deletion function = del_timer_sync()

Event History

May 21, 2024
CVE Published
via MITRE·02:35 PM
Data Sourced
via MITRE·02:35 PM
Description
Data Sourced
via OSV·03:15 PM
DescriptionSeverityAffected Software
Sep 4, 2025
Data Sourced
via Microsoft·04:41 AM
DescriptionSeverityWeakness

Frequently Asked Questions

1

What is the severity of CVE-2021-47324?

CVE-2021-47324 is classified as a high severity vulnerability due to its potential for exploitation in the Linux kernel.

2

How do I fix CVE-2021-47324?

To remediate CVE-2021-47324, users should update their Linux kernel to the latest patched version provided by their distribution.

3

What is the impact of CVE-2021-47324?

CVE-2021-47324 may allow an attacker to exploit a use-after-free condition, potentially leading to arbitrary code execution or system crashes.

4

Which versions of the Linux kernel are affected by CVE-2021-47324?

CVE-2021-47324 affects specific versions of the Linux kernel that incorporate the watchdog timer functionality, particularly prior to the fix.

5

Is CVE-2021-47324 publicly known?

Yes, CVE-2021-47324 is a publicly documented vulnerability that has been reported and acknowledged in the Linux community.

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