USN-4950-1: Linux kernel vulnerabilities

Releases

• Ubuntu 21.04

Packages

• linux - Linux kernel
• linux-aws - Linux kernel for Amazon Web Services (AWS) systems
• linux-azure - Linux kernel for Microsoft Azure Cloud systems
• linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
• linux-kvm - Linux kernel for cloud environments
• linux-oracle - Linux kernel for Oracle Cloud systems
• linux-raspi - Linux kernel for Raspberry Pi (V8) systems

Details

Ryota Shiga discovered that the eBPF implementation in the Linux kernel did
not properly verify that a BPF program only reserved as much memory for a
ring buffer as was allocated. A local attacker could use this to cause a
denial of service (system crash) or execute arbitrary code. (CVE-2021-3489)

Manfred Paul discovered that the eBPF implementation in the Linux kernel
did not properly track bounds on bitwise operations. A local attacker could
use this to cause a denial of service (system crash) or execute arbitrary
code. (CVE-2021-3490)

Billy Jheng Bing-Jhong discovered that the io_uring implementation of the
Linux kernel did not properly enforce the MAX_RW_COUNT limit in some
situations. A local attacker could use this to cause a denial of service
(system crash) or execute arbitrary code. (CVE-2021-3491)

Norbert Slusarek discovered that the CAN ISOTP protocol implementation
in the Linux kernel contained a race condition. A local attacker could
use this to cause a denial of service (system crash) or possibly
execute arbitrary code. Please note that to address this issue,
SF_BROADCAST support was removed temporarily from the CAN ISOTP
implementation in Ubuntu 21.04 kernels. (LP: #1927409)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.04

• linux-image-5.11.0-1005-azure - 5.11.0-1005.5
• linux-image-5.11.0-1006-oracle - 5.11.0-1006.6
• linux-image-5.11.0-1007-aws - 5.11.0-1007.7
• linux-image-5.11.0-1007-gcp - 5.11.0-1007.7
• linux-image-5.11.0-1007-kvm - 5.11.0-1007.7
• linux-image-5.11.0-1008-raspi - 5.11.0-1008.8
• linux-image-5.11.0-1008-raspi-nolpae - 5.11.0-1008.8
• linux-image-5.11.0-17-generic - 5.11.0-17.18
• linux-image-5.11.0-17-generic-64k - 5.11.0-17.18
• linux-image-5.11.0-17-generic-lpae - 5.11.0-17.18
• linux-image-5.11.0-17-lowlatency - 5.11.0-17.18
• linux-image-aws - 5.11.0.1007.7
• linux-image-azure - 5.11.0.1005.5
• linux-image-gcp - 5.11.0.1007.7
• linux-image-generic - 5.11.0.17.18
• linux-image-generic-64k - 5.11.0.17.18
• linux-image-generic-lpae - 5.11.0.17.18
• linux-image-gke - 5.11.0.1007.7
• linux-image-kvm - 5.11.0.1007.7
• linux-image-lowlatency - 5.11.0.17.18
• linux-image-oracle - 5.11.0.1006.6
• linux-image-raspi - 5.11.0.1008.6
• linux-image-raspi-nolpae - 5.11.0.1008.6
• linux-image-virtual - 5.11.0.17.18

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References

• CVE-2021-3489
• CVE-2021-3490
• CVE-2021-3491
• https://launchpad.net/bugs/1927409

Related notices

• USN-4948-1: linux-image-oem-20.04-edge, linux-image-5.10.0-1026-oem, linux-oem-5.10, linux-image-oem-20.04b
• USN-4949-1: linux-image-generic-lpae-hwe-20.04-edge, linux-image-gke, linux-image-generic-lpae-hwe-20.04, linux-image-5.8.0-1024-raspi-nolpae, linux-image-generic-64k-hwe-20.04-edge, linux-azure, linux-image-lowlatency-hwe-20.04, linux-image-raspi, linux-raspi, linux-aws, linux-image-generic, linux-image-oem-20.04, linux-image-aws, linux-image-gcp, linux-gcp, linux-image-5.8.0-53-lowlatency, linux, linux-oracle, linux-image-5.8.0-1024-raspi, linux-image-5.8.0-1032-azure, linux-image-5.8.0-53-generic, linux-image-virtual-hwe-20.04-edge, linux-image-5.8.0-1029-oracle, linux-image-5.8.0-53-generic-lpae, linux-image-kvm, linux-image-azure, linux-image-5.8.0-53-generic-64k, linux-image-generic-hwe-20.04, linux-image-generic-64k-hwe-20.04, linux-image-raspi-nolpae, linux-hwe-5.8, linux-image-5.8.0-1031-gcp, linux-image-5.8.0-1033-aws, linux-image-generic-hwe-20.04-edge, linux-image-generic-64k, linux-image-virtual-hwe-20.04, linux-image-lowlatency, linux-image-virtual, linux-image-5.8.0-1027-kvm, linux-image-oracle, linux-image-generic-lpae, linux-image-lowlatency-hwe-20.04-edge, linux-kvm