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AUSCERT External Security Bulletin Redistribution
ESB-2021.3871
LSN-0082-1: Kernel Live Patch Security Notice
12 November 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Linux Kernel Live Patch
Publisher: Ubuntu
Operating System: Ubuntu
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Denial of Service -- Existing Account
Access Confidential Data -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-3715 CVE-2021-3444 CVE-2020-29661
CVE-2020-29660
Reference: ESB-2021.3743
ESB-2021.3456
Original Bulletin:
https://ubuntu.com/security/notices/LSN-0082-1
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LSN-0082-1: Kernel Live Patch Security Notice
11 November 2021
Several security issues were fixed in the kernel.
Releases
o Ubuntu 20.04 LTS
o Ubuntu 18.04 LTS
o Ubuntu 16.04 ESM
Software Description
o gcp - Linux kernel for Google Cloud Platform (GCP) systems - (>=
5.4.0-1009)
o generic-4.15 - Linux hardware enablement (HWE) kernel - (>= 4.15.0-69, >=
4.15.0-143, >= 4.15.0-69)
o generic-4.4 - Linux kernel - (>= 4.4.0-211, >= 4.4.0-168)
o generic-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
o gke - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1033)
o gke-4.15 - Linux kernel for Google Container Engine (GKE) systems - (>=
4.15.0-1076)
o gke-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1009)
o gkeop - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1009)
o gkeop-5.4 - Linux kernel for Google Container Engine (GKE) systems - (>=
5.4.0-1007)
o lowlatency-4.15 - Linux hardware enablement (HWE) kernel - (>= 4.15.0-69, >
= 4.15.0-143, >= 4.15.0-69)
o lowlatency-4.4 - Linux kernel - (>= 4.4.0-211, >= 4.4.0-168)
o lowlatency-5.4 - Linux kernel - (>= 5.4.0-26, >= 5.4.0-26)
o oem - Linux kernel for OEM systems - (>= 4.15.0-1063)
Details
Jann Horn discovered that the tty subsystem of the Linux kernel did not use
consistent locking in some situations, leading to a read-after-free
vulnerability. A local attacker could use this to cause a denial of service
(system crash) or possibly expose sensitive information (kernel memory).(
CVE-2020-29660 )
Jann Horn discovered a race condition in the tty subsystem of the Linux
kernel in the locking for the TIOCSPGRP ioctl(), leading to a use-after-
free vulnerability. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code.( CVE-2020-29661 )
De4dCr0w of 360 Alpha Lab discovered that the BPF verifier in the Linux
kernel did not properly handle mod32 destination register truncation when
the source register was known to be 0. A local attacker could use this to
expose sensitive information (kernel memory) or possibly execute arbitrary
code.( CVE-2021-3444 )
kernel: use-after-free in route4_change() in
net/sched/cls_route.c( CVE-2021-3715 )
Checking update status
The problem can be corrected in these Livepatch versions:
Kernel type 20.04 18.04 16.04
gcp 82.2 - -
generic-4.15 - 82.2 82.2
generic-4.4 - - 82.2
generic-5.4 82.2 82.2 -
gke 82.2 - -
gke-4.15 - 82.2 -
gke-5.4 - 82.2 -
gkeop 82.2 - -
gkeop-5.4 - 82.2 -
lowlatency-4.15 - 82.2 82.2
lowlatency-4.4 - - 82.2
lowlatency-5.4 82.2 82.2 -
oem - 82.2 -
To check your kernel type and Livepatch version, enter this command:
canonical-livepatch status
References
o CVE-2020-29660
o CVE-2020-29661
o CVE-2021-3715
o CVE-2021-3444
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