CVE-2021-34556: Medium severity Linux Linux kernel vulnerability

Published Aug 2, 2021
·
Updated

In checkstackwritefixedoff and related functions of verifier.c, there is a possible out of bounds read due to side channel information disclosure. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.

Other sources

In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack.

— Launchpad

Affected Software

97 affected componentsFixes available
Linux Linux kernel<=5.13.7
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Debian Debian Linux=9.0
debian/linux
5.10.223-15.10.234-16.1.129-16.1.135-16.12.25-16.12.27-1
android/:linux_kernel:>=:0<:2022-06-05
:2022-06-05
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-azure*
ubuntu/linux-lts-xenial*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-hwe*
ubuntu/linux-azure*
ubuntu/linux-gcp*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-oracle*
ubuntu/linux-fips*
ubuntu/linux-fips*
ubuntu/linux-aws-5.4<5.4.0-1059.62~18.04.1
5.4.0-1059.62~18.04.1
ubuntu/linux-azure-5.4<5.4.0-1063.66~18.04.1
5.4.0-1063.66~18.04.1
ubuntu/linux-gcp-5.4<5.4.0-1057.61~18.04.1
5.4.0-1057.61~18.04.1
ubuntu/linux-gke-5.4<5.4.0-1055.58~18.04.1
5.4.0-1055.58~18.04.1
ubuntu/linux-gkeop-5.4<5.4.0-1026.27~18.04.1
5.4.0-1026.27~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-90.101~18.04.1
5.4.0-90.101~18.04.1
ubuntu/linux-oracle-5.4<5.4.0-1057.61~18.04.1
5.4.0-1057.61~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1046.50~18.04.1
5.4.0-1046.50~18.04.1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-4.15*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-4.15*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gcp-edge*
ubuntu/linux-gke-4.15*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-kvm*
ubuntu/linux-oem*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-90.101
5.4.0-90.101
ubuntu/linux-aws<5.4.0-1059.62
5.4.0-1059.62
ubuntu/linux-aws-5.11<5.11.0-1019.20~20.04.1
5.11.0-1019.20~20.04.1
ubuntu/linux-azure<5.4.0-1063.66
5.4.0-1063.66
ubuntu/linux-azure-5.11<5.11.0-1017.18~20.04.1
5.11.0-1017.18~20.04.1
ubuntu/linux-bluefield<5.4.0-1021.24
5.4.0-1021.24
ubuntu/linux-gcp<5.4.0-1057.61
5.4.0-1057.61
ubuntu/linux-gcp-5.11<5.11.0-1020.22~20.04.1
5.11.0-1020.22~20.04.1
ubuntu/linux-gke<5.4.0-1055.58
5.4.0-1055.58
ubuntu/linux-gkeop<5.4.0-1026.27
5.4.0-1026.27
ubuntu/linux-hwe-5.11<5.11.0-37.41~20.04.2
5.11.0-37.41~20.04.2
ubuntu/linux-ibm<5.4.0-1007.8
5.4.0-1007.8
ubuntu/linux-kvm<5.4.0-1049.51
5.4.0-1049.51
ubuntu/linux-oem-5.10<5.10.0-1050.52
5.10.0-1050.52
ubuntu/linux-oem-5.13<5.13.0-1014.18
5.13.0-1014.18
ubuntu/linux-oracle<5.4.0-1057.61
5.4.0-1057.61
ubuntu/linux-oracle-5.11<5.11.0-1019.20~20.04.1
5.11.0-1019.20~20.04.1
ubuntu/linux-raspi<5.4.0-1046.50
5.4.0-1046.50
ubuntu/linux-riscv-5.11<5.11.0-1020.21~20.04.1
5.11.0-1020.21~20.04.1
ubuntu/linux-aws-5.8*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde-5.15<5.15.0-1114.123~20.04.1
5.15.0-1114.123~20.04.1
ubuntu/linux-gcp-5.8*
ubuntu/linux-hwe-5.8*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
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<5.4.0-1036.42
5.4.0-1036.42
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-intel-iot-realtime*
ubuntu/linux-realtime*
ubuntu/linux-raspi-realtime*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

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

    Fixed in 5.10.223-1Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1
  2. Upgrade

    Upgrade android/:linux_kernel: to a version that resolves this vulnerability.

    Fixed in :2022-06-05
  3. Upgrade

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

    Fixed in 5.4.0-1059.62~18.04.1
  4. Upgrade

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

    Fixed in 5.4.0-1063.66~18.04.1
  5. Upgrade

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

    Fixed in 5.4.0-1057.61~18.04.1
  6. Upgrade

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

    Fixed in 5.4.0-1055.58~18.04.1
  7. Upgrade

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

    Fixed in 5.4.0-1026.27~18.04.1
  8. Upgrade

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

    Fixed in 5.4.0-90.101~18.04.1
  9. Upgrade

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

    Fixed in 5.4.0-1057.61~18.04.1
  10. Upgrade

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

    Fixed in 5.4.0-1046.50~18.04.1
  11. Upgrade

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

    Fixed in 5.4.0-90.101
  12. Upgrade

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

    Fixed in 5.4.0-1059.62
  13. Upgrade

    Upgrade ubuntu/linux-aws-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-1019.20~20.04.1
  14. Upgrade

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

    Fixed in 5.4.0-1063.66
  15. Upgrade

    Upgrade ubuntu/linux-azure-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-1017.18~20.04.1
  16. Upgrade

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

    Fixed in 5.4.0-1021.24
  17. Upgrade

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

    Fixed in 5.4.0-1057.61
  18. Upgrade

    Upgrade ubuntu/linux-gcp-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-1020.22~20.04.1
  19. Upgrade

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

    Fixed in 5.4.0-1055.58
  20. Upgrade

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

    Fixed in 5.4.0-1026.27
  21. Upgrade

    Upgrade ubuntu/linux-hwe-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-37.41~20.04.2
  22. Upgrade

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

    Fixed in 5.4.0-1007.8
  23. Upgrade

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

    Fixed in 5.4.0-1049.51
  24. Upgrade

    Upgrade ubuntu/linux-oem-5.10 to a version that resolves this vulnerability.

    Fixed in 5.10.0-1050.52
  25. Upgrade

    Upgrade ubuntu/linux-oem-5.13 to a version that resolves this vulnerability.

    Fixed in 5.13.0-1014.18
  26. Upgrade

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

    Fixed in 5.4.0-1057.61
  27. Upgrade

    Upgrade ubuntu/linux-oracle-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-1019.20~20.04.1
  28. Upgrade

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

    Fixed in 5.4.0-1046.50
  29. Upgrade

    Upgrade ubuntu/linux-riscv-5.11 to a version that resolves this vulnerability.

    Fixed in 5.11.0-1020.21~20.04.1
  30. Upgrade

    Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1114.123~20.04.1
  31. Upgrade

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

    Fixed in 5.4.0-1069.73+fips2
  32. Upgrade

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

    Fixed in 5.4.0-1073.76+fips1
  33. Upgrade

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

    Fixed in 5.4.0-1036.42
  34. Upgrade

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

    Fixed in 5.4.0-1067.71~20.04.1

Event History

Aug 2, 2021
CVE Published
via MITRE·04:02 AM
Data Sourced
via MITRE·04:02 AM
Description
Data Sourced
via OSV·05:15 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·05:15 AM
RemedyDescriptionSeverityWeaknessAffected Software
Jun 1, 2022
Advisory Published
via OSV·12:00 AM

Frequently Asked Questions

1

What is the severity of CVE-2021-34556?

CVE-2021-34556 has a high severity rating due to its potential to expose sensitive kernel memory to unprivileged BPF programs.

2

How does CVE-2021-34556 affect Linux kernel security?

CVE-2021-34556 allows an unprivileged user to exploit a side-channel attack to access sensitive information from kernel memory.

3

How do I fix CVE-2021-34556?

To resolve CVE-2021-34556, update to a version of the Linux kernel that is above 5.13.7 or apply the relevant patches.

4

Which versions of the Linux kernel are affected by CVE-2021-34556?

CVE-2021-34556 affects all versions of the Linux kernel up to and including 5.13.7.

5

What should I do if I cannot update my kernel affected by CVE-2021-34556?

If updating the kernel is not possible, consider applying security controls to limit BPF program capabilities until a patch can be implemented.

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