Use after free in Linux kernel - CVE-2020-25669

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Main Vulnerability Database Vulnerabilities #VU92762

Use after free in Linux kernel - CVE-2020-25669

Published: May 26, 2021 / Updated: February 24, 2023


Vulnerability identifier: #VU92762
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-25669
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to execute arbitrary code.

A vulnerability was found in the Linux Kernel where the function sunkbd_reinit having been scheduled by sunkbd_interrupt before sunkbd being freed. Though the dangling pointer is set to NULL in sunkbd_disconnect, there is still an alias in sunkbd_reinit causing Use After Free.


Affected software

Linux kernel
Amazon Linux AMI
Ubuntu
openEuler
linux-image-lowlatency-lts-xenial (Ubuntu package)
linux-image-virtual-lts-xenial (Ubuntu package)
linux-image-powerpc64-smp-lts-xenial (Ubuntu package)
linux-image-powerpc64-emb-lts-xenial (Ubuntu package)
linux-image-powerpc-smp-lts-xenial (Ubuntu package)
linux-image-powerpc-e500mc-lts-xenial (Ubuntu package)
linux-image-generic-lts-xenial (Ubuntu package)
linux-image-generic-lpae-lts-xenial (Ubuntu package)
linux-image-lowlatency (Ubuntu package)
linux-image-virtual (Ubuntu package)
linux-image-powerpc64-smp (Ubuntu package)
linux-image-powerpc64-emb (Ubuntu package)
linux-image-powerpc-smp (Ubuntu package)
linux-image-powerpc-e500mc (Ubuntu package)
linux-image-generic-lpae (Ubuntu package)
linux-image-generic (Ubuntu package)
linux-image-4.4.0-201-generic-lpae (Ubuntu package)
linux-image-4.4.0-201-generic (Ubuntu package)
linux-image-4.4.0-201-powerpc64-smp (Ubuntu package)
linux-image-4.4.0-201-powerpc64-emb (Ubuntu package)
linux-image-4.4.0-201-powerpc-smp (Ubuntu package)
linux-image-4.4.0-201-powerpc-e500mc (Ubuntu package)
linux-image-4.4.0-201-lowlatency (Ubuntu package)
linux-image-aws (Ubuntu package)
linux-image-4.4.0-1085-aws (Ubuntu package)
linux-image-kvm (Ubuntu package)
linux-image-4.4.0-1087-kvm (Ubuntu package)
linux-image-4.4.0-1121-aws (Ubuntu package)
linux-image-raspi2 (Ubuntu package)
linux-image-4.4.0-1145-raspi2 (Ubuntu package)
linux-image-snapdragon (Ubuntu package)
linux-image-4.4.0-1149-snapdragon (Ubuntu package)
kernel
linux-image-generic-hwe-16.04 (Ubuntu package)
linux-image-generic-lpae-hwe-16.04 (Ubuntu package)
linux-image-lowlatency-hwe-16.04 (Ubuntu package)
linux-image-oem (Ubuntu package)
linux-image-virtual-hwe-16.04 (Ubuntu package)
linux-image-4.15.0-136-generic (Ubuntu package)
linux-image-4.15.0-136-generic-lpae (Ubuntu package)
linux-image-4.15.0-136-lowlatency (Ubuntu package)
linux-image-dell300x (Ubuntu package)
linux-image-4.15.0-1012-dell300x (Ubuntu package)
linux-image-oracle (Ubuntu package)
linux-image-4.15.0-1065-oracle (Ubuntu package)
linux-image-oracle-lts-18.04 (Ubuntu package)
linux-image-gke-4.15 (Ubuntu package)
linux-image-gke (Ubuntu package)
linux-image-4.15.0-1079-gke (Ubuntu package)
linux-image-4.15.0-1079-raspi2 (Ubuntu package)
linux-image-4.15.0-1085-kvm (Ubuntu package)
linux-image-gcp (Ubuntu package)
linux-image-4.15.0-1093-gcp (Ubuntu package)
linux-image-gcp-lts-18.04 (Ubuntu package)
linux-image-aws-hwe (Ubuntu package)
linux-image-aws-lts-18.04 (Ubuntu package)
linux-image-4.15.0-1094-aws (Ubuntu package)
linux-image-4.15.0-1096-snapdragon (Ubuntu package)
linux-image-azure-lts-18.04 (Ubuntu package)
linux-image-azure (Ubuntu package)
linux-image-4.15.0-1108-azure (Ubuntu package)
perf
python2-perf-debuginfo
kernel-source
kernel-tools-debuginfo
kernel-devel
kernel-tools-devel
bpftool-debuginfo
python3-perf
python2-perf
python3-perf-debuginfo
perf-debuginfo
kernel-debuginfo
kernel-tools
kernel-debugsource
bpftool
linux-image-oem-osp1 (Ubuntu package)
linux-image-5.4.0-66-lowlatency (Ubuntu package)
linux-image-5.4.0-66-generic-lpae (Ubuntu package)
linux-image-5.4.0-66-generic (Ubuntu package)
linux-image-generic-hwe-18.04 (Ubuntu package)
linux-image-generic-lpae-hwe-18.04 (Ubuntu package)
linux-image-lowlatency-hwe-18.04 (Ubuntu package)
linux-image-snapdragon-hwe-18.04 (Ubuntu package)
linux-image-virtual-hwe-18.04 (Ubuntu package)
linux-image-5.4.0-1010-gkeop (Ubuntu package)
linux-image-gkeop-5.4 (Ubuntu package)
linux-image-gkeop (Ubuntu package)
linux-image-raspi-hwe-18.04 (Ubuntu package)
linux-image-5.4.0-1029-raspi (Ubuntu package)
linux-image-raspi (Ubuntu package)
linux-image-5.4.0-1033-kvm (Ubuntu package)
linux-image-5.4.0-1036-gke (Ubuntu package)
linux-image-gke-5.4 (Ubuntu package)
linux-image-5.4.0-1037-gcp (Ubuntu package)
linux-image-5.4.0-1038-aws (Ubuntu package)
linux-image-5.4.0-1038-oracle (Ubuntu package)
linux-image-5.4.0-1040-azure (Ubuntu package)
linux-image-oem-20.04 (Ubuntu package)
linux-image-5.6.0-1053-oem (Ubuntu package)
linux-image-generic-64k (Ubuntu package)
linux-image-5.8.0-44-generic-64k (Ubuntu package)
linux-image-5.8.0-44-lowlatency (Ubuntu package)
linux-image-5.8.0-44-generic-lpae (Ubuntu package)
linux-image-5.8.0-44-generic (Ubuntu package)
linux-image-generic-64k-hwe-20.04 (Ubuntu package)
linux-image-generic-hwe-20.04 (Ubuntu package)
linux-image-generic-lpae-hwe-20.04 (Ubuntu package)
linux-image-lowlatency-hwe-20.04 (Ubuntu package)
linux-image-virtual-hwe-20.04 (Ubuntu package)
linux-image-5.8.0-1016-raspi-nolpae (Ubuntu package)
linux-image-5.8.0-1016-raspi (Ubuntu package)
linux-image-raspi-nolpae (Ubuntu package)
linux-image-5.8.0-1019-kvm (Ubuntu package)
linux-image-5.8.0-1021-oracle (Ubuntu package)
linux-image-5.8.0-1023-gcp (Ubuntu package)
linux-image-5.8.0-1023-azure (Ubuntu package)
linux-image-5.8.0-1024-aws (Ubuntu package)

How to mitigate CVE-2020-25669

Install update from vendor's repository.

linux-image-lowlatency-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-virtual-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-powerpc64-smp-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-powerpc64-emb-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-powerpc-smp-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-powerpc-e500mc-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-generic-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-generic-lpae-lts-xenial (Ubuntu package) - update to 4.4.0.201.176
linux-image-lowlatency (Ubuntu package) - addressed in versions 4.4.0.201.207, 4.15.0.136.123, 5.4.0.66.69, 5.8.0.44.49
linux-image-virtual (Ubuntu package) - addressed in versions 4.4.0.201.207, 4.15.0.136.123, 5.4.0.66.69, 5.8.0.44.49
linux-image-powerpc64-smp (Ubuntu package) - update to 4.4.0.201.207
linux-image-powerpc64-emb (Ubuntu package) - update to 4.4.0.201.207
linux-image-powerpc-smp (Ubuntu package) - update to 4.4.0.201.207
linux-image-powerpc-e500mc (Ubuntu package) - update to 4.4.0.201.207
linux-image-generic-lpae (Ubuntu package) - addressed in versions 4.4.0.201.207, 4.15.0.136.123, 5.4.0.66.69, 5.8.0.44.49
linux-image-generic (Ubuntu package) - addressed in versions 4.4.0.201.207, 4.15.0.136.123, 5.4.0.66.69, 5.8.0.44.49
linux-image-4.4.0-201-generic-lpae (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-generic (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc64-smp (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc64-emb (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc-smp (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-powerpc-e500mc (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-4.4.0-201-lowlatency (Ubuntu package) - update to 4.4.0-201.233~14.04.1
linux-image-aws (Ubuntu package) - addressed in versions 4.4.0.1085.82, 4.4.0.1121.126, 5.4.0.1038.22, 5.4.0.1038.39, 5.8.0.1024.26
linux-image-4.4.0-1085-aws (Ubuntu package) - update to 4.4.0-1085.89
linux-image-kvm (Ubuntu package) - addressed in versions 4.4.0.1087.85, 4.15.0.1085.81, 5.4.0.1033.31, 5.8.0.1019.21
linux-image-4.4.0-1087-kvm (Ubuntu package) - update to 4.4.0-1087.96
linux-image-4.4.0-1121-aws (Ubuntu package) - update to 4.4.0-1121.135
linux-image-raspi2 (Ubuntu package) - addressed in versions 4.4.0.1145.145, 4.15.0.1079.76, 5.4.0.1029.64
linux-image-4.4.0-1145-raspi2 (Ubuntu package) - update to 4.4.0-1145.155
linux-image-snapdragon (Ubuntu package) - addressed in versions 4.4.0.1149.141, 4.15.0.1096.99
linux-image-4.4.0-1149-snapdragon (Ubuntu package) - update to 4.4.0-1149.159
kernel - update to 4.14.209-117.337
linux-image-generic-hwe-16.04 (Ubuntu package) - update to 4.15.0.136.132
linux-image-generic-lpae-hwe-16.04 (Ubuntu package) - update to 4.15.0.136.132
linux-image-lowlatency-hwe-16.04 (Ubuntu package) - update to 4.15.0.136.132
linux-image-oem (Ubuntu package) - addressed in versions 4.15.0.136.132, 5.4.0.66.69, 5.4.0.66.74~18.04.61
linux-image-virtual-hwe-16.04 (Ubuntu package) - update to 4.15.0.136.132
linux-image-4.15.0-136-generic (Ubuntu package) - update to 4.15.0-136.140~16.04.1
linux-image-4.15.0-136-generic-lpae (Ubuntu package) - update to 4.15.0-136.140~16.04.1
linux-image-4.15.0-136-lowlatency (Ubuntu package) - update to 4.15.0-136.140~16.04.1
linux-image-dell300x (Ubuntu package) - update to 4.15.0.1012.14
linux-image-4.15.0-1012-dell300x (Ubuntu package) - update to 4.15.0-1012.16
linux-image-oracle (Ubuntu package) - addressed in versions 4.15.0.1065.53, 5.4.0.1038.35, 5.4.0.1038.41~18.04.21, 5.8.0.1021.20
linux-image-4.15.0-1065-oracle (Ubuntu package) - update to 4.15.0-1065.73~16.04.1
linux-image-oracle-lts-18.04 (Ubuntu package) - update to 4.15.0.1065.75
linux-image-gke-4.15 (Ubuntu package) - update to 4.15.0.1079.83
linux-image-gke (Ubuntu package) - addressed in versions 4.15.0.1079.83, 4.15.0.1093.94, 5.8.0.1023.23
linux-image-4.15.0-1079-gke (Ubuntu package) - update to 4.15.0-1079.84
linux-image-4.15.0-1079-raspi2 (Ubuntu package) - update to 4.15.0-1079.84
linux-image-4.15.0-1085-kvm (Ubuntu package) - update to 4.15.0-1085.87
linux-image-gcp (Ubuntu package) - addressed in versions 4.15.0.1093.94, 5.4.0.1037.24, 5.4.0.1037.46, 5.8.0.1023.23
linux-image-4.15.0-1093-gcp (Ubuntu package) - update to 4.15.0-1093.106~16.04.1
linux-image-gcp-lts-18.04 (Ubuntu package) - update to 4.15.0.1093.111
linux-image-aws-hwe (Ubuntu package) - update to 4.15.0.1094.87
linux-image-aws-lts-18.04 (Ubuntu package) - update to 4.15.0.1094.97
linux-image-4.15.0-1094-aws (Ubuntu package) - update to 4.15.0-1094.101~16.04.1
linux-image-4.15.0-1096-snapdragon (Ubuntu package) - update to 4.15.0-1096.105
linux-image-azure-lts-18.04 (Ubuntu package) - update to 4.15.0.1108.81
linux-image-azure (Ubuntu package) - addressed in versions 4.15.0.1108.81, 4.15.0.1108.99, 5.4.0.1040.20, 5.4.0.1040.38, 5.8.0.1023.23
linux-image-4.15.0-1108-azure (Ubuntu package) - addressed in versions 4.15.0-1108.120~14.04.1, 4.15.0-1108.120~16.04.1
perf - update to 4.19.90-2011.6.0.0049
python2-perf-debuginfo - update to 4.19.90-2011.6.0.0049
kernel-source - update to 4.19.90-2011.6.0.0049
kernel - update to 4.19.90-2011.6.0.0049
kernel-tools-debuginfo - update to 4.19.90-2011.6.0.0049
kernel-devel - update to 4.19.90-2011.6.0.0049
kernel-tools-devel - update to 4.19.90-2011.6.0.0049
bpftool-debuginfo - update to 4.19.90-2011.6.0.0049
python3-perf - update to 4.19.90-2011.6.0.0049
python2-perf - update to 4.19.90-2011.6.0.0049
python3-perf-debuginfo - update to 4.19.90-2011.6.0.0049
perf-debuginfo - update to 4.19.90-2011.6.0.0049
kernel-debuginfo - update to 4.19.90-2011.6.0.0049
kernel-tools - update to 4.19.90-2011.6.0.0049
kernel-debugsource - update to 4.19.90-2011.6.0.0049
bpftool - update to 4.19.90-2011.6.0.0049
linux-image-oem-osp1 (Ubuntu package) - addressed in versions 5.4.0.66.69, 5.4.0.66.74~18.04.61
linux-image-5.4.0-66-lowlatency (Ubuntu package) - addressed in versions 5.4.0-66.74, 5.4.0-66.74~18.04.2
linux-image-5.4.0-66-generic-lpae (Ubuntu package) - addressed in versions 5.4.0-66.74, 5.4.0-66.74~18.04.2
linux-image-5.4.0-66-generic (Ubuntu package) - addressed in versions 5.4.0-66.74, 5.4.0-66.74~18.04.2
linux-image-generic-hwe-18.04 (Ubuntu package) - update to 5.4.0.66.74~18.04.61
linux-image-generic-lpae-hwe-18.04 (Ubuntu package) - update to 5.4.0.66.74~18.04.61
linux-image-lowlatency-hwe-18.04 (Ubuntu package) - update to 5.4.0.66.74~18.04.61
linux-image-snapdragon-hwe-18.04 (Ubuntu package) - update to 5.4.0.66.74~18.04.61
linux-image-virtual-hwe-18.04 (Ubuntu package) - update to 5.4.0.66.74~18.04.61
linux-image-5.4.0-1010-gkeop (Ubuntu package) - addressed in versions 5.4.0-1010.11, 5.4.0-1010.11~18.04.1
linux-image-gkeop-5.4 (Ubuntu package) - addressed in versions 5.4.0.1010.11~18.04.11, 5.4.0.1010.13
linux-image-gkeop (Ubuntu package) - update to 5.4.0.1010.13
linux-image-raspi-hwe-18.04 (Ubuntu package) - update to 5.4.0.1029.32
linux-image-5.4.0-1029-raspi (Ubuntu package) - addressed in versions 5.4.0-1029.32, 5.4.0-1029.32~18.04.1
linux-image-raspi (Ubuntu package) - addressed in versions 5.4.0.1029.64, 5.8.0.1016.19
linux-image-5.4.0-1033-kvm (Ubuntu package) - update to 5.4.0-1033.34
linux-image-5.4.0-1036-gke (Ubuntu package) - update to 5.4.0-1036.38~18.04.1
linux-image-gke-5.4 (Ubuntu package) - update to 5.4.0.1036.38~18.04.4
linux-image-5.4.0-1037-gcp (Ubuntu package) - addressed in versions 5.4.0-1037.40, 5.4.0-1037.40~18.04.1
linux-image-5.4.0-1038-aws (Ubuntu package) - addressed in versions 5.4.0-1038.40, 5.4.0-1038.40~18.04.1
linux-image-5.4.0-1038-oracle (Ubuntu package) - addressed in versions 5.4.0-1038.41, 5.4.0-1038.41~18.04.1
linux-image-5.4.0-1040-azure (Ubuntu package) - addressed in versions 5.4.0-1040.42, 5.4.0-1040.42~18.04.1
linux-image-oem-20.04 (Ubuntu package) - addressed in versions 5.6.0.1053.49, 5.8.0.44.49
linux-image-5.6.0-1053-oem (Ubuntu package) - update to 5.6.0-1053.57
linux-image-generic-64k (Ubuntu package) - update to 5.8.0.44.49
linux-image-5.8.0-44-generic-64k (Ubuntu package) - update to 5.8.0-44.50
linux-image-5.8.0-44-lowlatency (Ubuntu package) - update to 5.8.0-44.50~20.04.1
linux-image-5.8.0-44-generic-lpae (Ubuntu package) - update to 5.8.0-44.50~20.04.1
linux-image-5.8.0-44-generic (Ubuntu package) - update to 5.8.0-44.50~20.04.1
linux-image-generic-64k-hwe-20.04 (Ubuntu package) - update to 5.8.0.44.50~20.04.30
linux-image-generic-hwe-20.04 (Ubuntu package) - update to 5.8.0.44.50~20.04.30
linux-image-generic-lpae-hwe-20.04 (Ubuntu package) - update to 5.8.0.44.50~20.04.30
linux-image-lowlatency-hwe-20.04 (Ubuntu package) - update to 5.8.0.44.50~20.04.30
linux-image-virtual-hwe-20.04 (Ubuntu package) - update to 5.8.0.44.50~20.04.30
linux-image-5.8.0-1016-raspi-nolpae (Ubuntu package) - update to 5.8.0-1016.19
linux-image-5.8.0-1016-raspi (Ubuntu package) - update to 5.8.0-1016.19
linux-image-raspi-nolpae (Ubuntu package) - update to 5.8.0.1016.19
linux-image-5.8.0-1019-kvm (Ubuntu package) - update to 5.8.0-1019.21
linux-image-5.8.0-1021-oracle (Ubuntu package) - update to 5.8.0-1021.22
linux-image-5.8.0-1023-gcp (Ubuntu package) - update to 5.8.0-1023.24
linux-image-5.8.0-1023-azure (Ubuntu package) - update to 5.8.0-1023.25
linux-image-5.8.0-1024-aws (Ubuntu package) - update to 5.8.0-1024.26

External References

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