CVE-2020-28974: Medium severity Linux Linux kernel vulnerability

Published Nov 9, 2020
·
Updated

A slab-out-of-bounds read in fbcon in the Linux kernel before 5.9.7 could be used by local attackers to read privileged information or potentially crash the kernel, aka CID-3c4e0dff2095. This occurs because KDFONTOPCOPY in drivers/tty/vt/vt.c can be used for manipulations such as font height.

Other sources

An out-of-bounds (OOB) SLAB memory access flaw was found in the fbcon driver module in the Linux kernel. A bounds check failure allows a local attacker with special user privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

This occurs because KDFONTOPCOPY in drivers/tty/vt/vt.c can be used for manipulations such as font height.

References: http://www.openwall.com/lists/oss-security/2020/11/25/1 https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.9.7 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3c4e0dff2095c579b142d5a0693257f1c58b4804 https://seclists.org/oss-sec/2020/q4/104

— Red Hat

An out-of-bounds (OOB) SLAB memory access flaw was found in the Linux kernel's fbcon driver module. A bounds check failure allows a local attacker with special user privileges to gain access to out-of-bounds memory, leading to a system crash or leaking of internal kernel information. The highest threat from this vulnerability is to system availability.

Affected Software

83 affected componentsFixes available
redhat/kernel-rt<0:4.18.0-305.rt7.72.el8
0:4.18.0-305.rt7.72.el8
redhat/kernel<0:4.18.0-305.el8
0:4.18.0-305.el8
Linux Linux kernel<5.9.7
Debian Debian Linux=9.0
debian/linux
5.10.223-15.10.234-16.1.129-16.1.135-16.12.25-1
ubuntu/linux-aws<4.4.0-1083.87
4.4.0-1083.87
ubuntu/linux-azure<4.15.0-1103.114~14.04.1
4.15.0-1103.114~14.04.1
ubuntu/linux-lts-xenial<4.4.0-198.230~14.04.1
4.4.0-198.230~14.04.1
ubuntu/linux*
ubuntu/linux<4.4.0-198.230
4.4.0-198.230
ubuntu/linux-aws<4.4.0-1119.133
4.4.0-1119.133
ubuntu/linux-aws-hwe<4.15.0-1091.96~16.04.1
4.15.0-1091.96~16.04.1
ubuntu/linux-azure<4.15.0-1103.114~16.04.1
4.15.0-1103.114~16.04.1
ubuntu/linux-gcp<4.15.0-1091.104~16.04.1
4.15.0-1091.104~16.04.1
ubuntu/linux-hwe<4.15.0-129.132~16.04.1
4.15.0-129.132~16.04.1
ubuntu/linux-kvm<4.4.0-1085.94
4.4.0-1085.94
ubuntu/linux-oracle<4.15.0-1062.68~16.04.1
4.15.0-1062.68~16.04.1
ubuntu/linux-raspi2<4.4.0-1143.153
4.4.0-1143.153
ubuntu/linux-snapdragon<4.4.0-1147.157
4.4.0-1147.157
ubuntu/linux-hwe-edge*
ubuntu/linux-fips<4.4.0-1052.58
4.4.0-1052.58
ubuntu/linux-fips*
ubuntu/linux<4.15.0-129.132
4.15.0-129.132
ubuntu/linux-aws<4.15.0-1091.96
4.15.0-1091.96
ubuntu/linux-aws-5.4<5.4.0-1034.35~18.04.1
5.4.0-1034.35~18.04.1
ubuntu/linux-azure-4.15<4.15.0-1103.114
4.15.0-1103.114
ubuntu/linux-azure-5.4<5.4.0-1035.36~18.04.1
5.4.0-1035.36~18.04.1
ubuntu/linux-dell300x<4.15.0-1010.14
4.15.0-1010.14
ubuntu/linux-gcp-4.15<4.15.0-1091.104
4.15.0-1091.104
ubuntu/linux-gcp-5.4<5.4.0-1033.35~18.04.1
5.4.0-1033.35~18.04.1
ubuntu/linux-gke-4.15<4.15.0-1077.82
4.15.0-1077.82
ubuntu/linux-gke-5.4<5.4.0-1033.35~18.04.1
5.4.0-1033.35~18.04.1
ubuntu/linux-gkeop-5.4<5.4.0-1008.9~18.04.1
5.4.0-1008.9~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-59.65~18.04.1
5.4.0-59.65~18.04.1
ubuntu/linux-kvm<4.15.0-1082.84
4.15.0-1082.84
ubuntu/linux-oracle<4.15.0-1062.68
4.15.0-1062.68
ubuntu/linux-oracle-5.4<5.4.0-1034.36~18.04.1
5.4.0-1034.36~18.04.1
ubuntu/linux-raspi-5.4<5.4.0-1026.29~18.04.1
5.4.0-1026.29~18.04.1
ubuntu/linux-raspi2<4.15.0-1077.82
4.15.0-1077.82
ubuntu/linux-snapdragon<4.15.0-1094.103
4.15.0-1094.103
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-gcp-edge*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-aws-fips<4.15.0-2034.35
4.15.0-2034.35
ubuntu/linux-azure-fips<4.15.0-2016.18
4.15.0-2016.18
ubuntu/linux-fips<4.15.0-1049.56
4.15.0-1049.56
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.4.0-59.65
5.4.0-59.65
ubuntu/linux-aws<5.4.0-1034.35
5.4.0-1034.35
ubuntu/linux-azure<5.4.0-1035.36
5.4.0-1035.36
ubuntu/linux-gcp<5.4.0-1033.35
5.4.0-1033.35
ubuntu/linux-hwe-5.8<5.8.0-44.50~20.04.1
5.8.0-44.50~20.04.1
ubuntu/linux-kvm<5.4.0-1031.32
5.4.0-1031.32
ubuntu/linux-oem-5.6<5.6.0-1039.43
5.6.0-1039.43
ubuntu/linux-oracle<5.4.0-1034.36
5.4.0-1034.36
ubuntu/linux-raspi<5.4.0-1026.29
5.4.0-1026.29
ubuntu/linux-riscv<5.4.0-40.45
5.4.0-40.45
ubuntu/linux-riscv-5.8<5.8.0-17.19~20.04.1
5.8.0-17.19~20.04.1
ubuntu/linux-azure-fde-5.15<5.15.0-1114.123~20.04.1
5.15.0-1114.123~20.04.1
ubuntu/linux-raspi2*
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-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-gcp-fips*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-realtime*
ubuntu/linux-raspi-realtime*
ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/kernel-rt to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-305.rt7.72.el8
  2. Upgrade

    Upgrade redhat/kernel to a version that resolves this vulnerability.

    Fixed in 0:4.18.0-305.el8
  3. 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 6.12.25-1
  4. Upgrade

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

    Fixed in 4.4.0-1083.87
  5. Upgrade

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

    Fixed in 4.15.0-1103.114~14.04.1
  6. Upgrade

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

    Fixed in 4.4.0-198.230~14.04.1
  7. Upgrade

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

    Fixed in 4.4.0-198.230
  8. Upgrade

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

    Fixed in 4.4.0-1119.133
  9. Upgrade

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

    Fixed in 4.15.0-1091.96~16.04.1
  10. Upgrade

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

    Fixed in 4.15.0-1103.114~16.04.1
  11. Upgrade

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

    Fixed in 4.15.0-1091.104~16.04.1
  12. Upgrade

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

    Fixed in 4.15.0-129.132~16.04.1
  13. Upgrade

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

    Fixed in 4.4.0-1085.94
  14. Upgrade

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

    Fixed in 4.15.0-1062.68~16.04.1
  15. Upgrade

    Upgrade ubuntu/linux-raspi2 to a version that resolves this vulnerability.

    Fixed in 4.4.0-1143.153
  16. Upgrade

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

    Fixed in 4.4.0-1147.157
  17. Upgrade

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

    Fixed in 4.4.0-1052.58
  18. Upgrade

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

    Fixed in 4.15.0-129.132
  19. Upgrade

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

    Fixed in 4.15.0-1091.96
  20. Upgrade

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

    Fixed in 5.4.0-1034.35~18.04.1
  21. Upgrade

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

    Fixed in 4.15.0-1103.114
  22. Upgrade

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

    Fixed in 5.4.0-1035.36~18.04.1
  23. Upgrade

    Upgrade ubuntu/linux-dell300x to a version that resolves this vulnerability.

    Fixed in 4.15.0-1010.14
  24. Upgrade

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

    Fixed in 4.15.0-1091.104
  25. Upgrade

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

    Fixed in 5.4.0-1033.35~18.04.1
  26. Upgrade

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

    Fixed in 4.15.0-1077.82
  27. Upgrade

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

    Fixed in 5.4.0-1033.35~18.04.1
  28. Upgrade

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

    Fixed in 5.4.0-1008.9~18.04.1
  29. Upgrade

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

    Fixed in 5.4.0-59.65~18.04.1
  30. Upgrade

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

    Fixed in 4.15.0-1082.84
  31. Upgrade

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

    Fixed in 4.15.0-1062.68
  32. Upgrade

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

    Fixed in 5.4.0-1034.36~18.04.1
  33. Upgrade

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

    Fixed in 5.4.0-1026.29~18.04.1
  34. Upgrade

    Upgrade ubuntu/linux-raspi2 to a version that resolves this vulnerability.

    Fixed in 4.15.0-1077.82
  35. Upgrade

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

    Fixed in 4.15.0-1094.103
  36. Upgrade

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

    Fixed in 4.15.0-2034.35
  37. Upgrade

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

    Fixed in 4.15.0-2016.18
  38. Upgrade

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

    Fixed in 4.15.0-1049.56
  39. Upgrade

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

    Fixed in 5.4.0-59.65
  40. Upgrade

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

    Fixed in 5.4.0-1034.35
  41. Upgrade

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

    Fixed in 5.4.0-1035.36
  42. Upgrade

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

    Fixed in 5.4.0-1033.35
  43. Upgrade

    Upgrade ubuntu/linux-hwe-5.8 to a version that resolves this vulnerability.

    Fixed in 5.8.0-44.50~20.04.1
  44. Upgrade

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

    Fixed in 5.4.0-1031.32
  45. Upgrade

    Upgrade ubuntu/linux-oem-5.6 to a version that resolves this vulnerability.

    Fixed in 5.6.0-1039.43
  46. Upgrade

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

    Fixed in 5.4.0-1034.36
  47. Upgrade

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

    Fixed in 5.4.0-1026.29
  48. Upgrade

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

    Fixed in 5.4.0-40.45
  49. Upgrade

    Upgrade ubuntu/linux-riscv-5.8 to a version that resolves this vulnerability.

    Fixed in 5.8.0-17.19~20.04.1
  50. 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
  51. Upgrade

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

    Fixed in 5.4.0-1069.73+fips2
  52. Upgrade

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

    Fixed in 5.4.0-1073.76+fips1
  53. Upgrade

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

    Fixed in 5.4.0-1067.71~20.04.1
  54. Upgrade

    Upgrade Linux kernel to a version that resolves this vulnerability.

    Fixed in 5.9.7
  55. Configuration

    Add the 'nomodeset' kernel boot parameter in /etc/default/grub to disable frame buffering; this mitigation applies to RHEL7/RHEL8. Run 'grub2-mkconfig -o /boot/grub2/grub.cfg' and reboot.

    Linux kernel fbcon/frame buffering nomodeset = enabled

Event History

Nov 9, 2020
CVE Published
12:00 AM
Nov 20, 2020
CVE Published
via MITRE·05:49 PM
Data Sourced
via MITRE·05:49 PM
Description
Data Sourced
via OSV·06:15 PM
DescriptionSeverityAffected Software
Dec 1, 2020
Data Sourced
via Red Hat·12:03 PM
DescriptionSeverityAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is the severity of CVE-2020-28974?

CVE-2020-28974 is considered to have a moderate severity level due to its potential to allow local attackers to read privileged information.

2

How do I fix CVE-2020-28974?

To fix CVE-2020-28974, upgrade your Linux kernel to version 5.9.7 or later, or apply the specific patches recommended for affected distributions.

3

What versions of the Linux kernel are affected by CVE-2020-28974?

CVE-2020-28974 affects Linux kernel versions prior to 5.9.7.

4

Can CVE-2020-28974 cause system crashes?

Yes, CVE-2020-28974 has the potential to crash the kernel under certain conditions.

5

Which Linux distributions are impacted by CVE-2020-28974?

CVE-2020-28974 affects various distributions using the Linux kernel, including specific versions found in Red Hat and Debian.

Company

Resources

Contact

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