USN-6416-2: Linux kernel vulnerabilities

6 October 2023

Several security issues were fixed in the Linux kernel.

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Details

It was discovered that the IPv6 implementation in the Linux kernel
contained a high rate of hash collisions in connection lookup table. A
remote attacker could use this to cause a denial of service (excessive CPU
consumption). (CVE-2023-1206)

Daniël Trujillo, Johannes Wikner, and Kaveh Razavi discovered that some AMD
processors utilising speculative execution and branch prediction may allow
unauthorised memory reads via a speculative side-channel attack. A local
attacker could use this to expose sensitive information, including kernel
memory. (CVE-2023-20569)

It was discovered that the IPv6 RPL protocol implementation in the Linux
kernel did not properly handle user-supplied data. A remote attacker could
use this to cause a denial of service (system crash). (CVE-2023-2156)

Davide Ornaghi discovered that the DECnet network protocol implementation
in the Linux kernel contained a null pointer dereference vulnerability. A
remote attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. Please note that kernel support for the
DECnet has been removed to resolve this CVE. (CVE-2023-3338)

Chih-Yen Chang discovered that the KSMBD implementation in the Linux kernel
did not properly validate command payload size, leading to a out-of-bounds
read vulnerability. A remote attacker could possibly use this to cause a
denial of service (system crash). (CVE-2023-38432)

It was discovered that the NFC implementation in the Linux kernel contained
a use-after-free vulnerability when performing peer-to-peer communication
in certain conditions. A privileged attacker could use this to cause a
denial of service (system crash) or possibly expose sensitive information
(kernel memory). (CVE-2023-3863)

Laurence Wit discovered that the KSMBD implementation in the Linux kernel
did not properly validate a buffer size in certain situations, leading to
an out-of-bounds read vulnerability. A remote attacker could use this to
cause a denial of service (system crash) or possibly expose sensitive
information. (CVE-2023-3865)

Laurence Wit discovered that the KSMBD implementation in the Linux kernel
contained a null pointer dereference vulnerability when handling handling
chained requests. A remote attacker could use this to cause a denial of
service (system crash). (CVE-2023-3866)

It was discovered that the Siano USB MDTV receiver device driver in the
Linux kernel did not properly handle device initialization failures in
certain situations, leading to a use-after-free vulnerability. A physically
proximate attacker could use this cause a denial of service (system crash).
(CVE-2023-4132)

Andy Nguyen discovered that the KVM implementation for AMD processors in
the Linux kernel with Secure Encrypted Virtualization (SEV) contained a
race condition when accessing the GHCB page. A local attacker in a SEV
guest VM could possibly use this to cause a denial of service (host system
crash). (CVE-2023-4155)

It was discovered that the TUN/TAP driver in the Linux kernel did not
properly initialize socket data. A local attacker could use this to cause a
denial of service (system crash). (CVE-2023-4194)

Maxim Suhanov discovered that the exFAT file system implementation in the
Linux kernel did not properly check a file name length, leading to an out-
of-bounds write vulnerability. An attacker could use this to construct a
malicious exFAT image that, when mounted and operated on, could cause a
denial of service (system crash) or possibly execute arbitrary code.
(CVE-2023-4273)

Thelford Williams discovered that the Ceph file system messenger protocol
implementation in the Linux kernel did not properly validate frame segment
length in certain situation, leading to a buffer overflow vulnerability. A
remote attacker could use this to cause a denial of service (system crash)
or possibly execute arbitrary code. (CVE-2023-44466)

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Update instructions

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

Ubuntu 20.04

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.

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