USN-4752-1: Linux kernel (OEM) vulnerabilities
25 February 2021
Several security issues were fixed in the Linux kernel.
Releases
Packages
- linux-oem-5.6 - Linux kernel for OEM systems
Details
Daniele Antonioli, Nils Ole Tippenhauer, and Kasper Rasmussen discovered
that legacy pairing and secure-connections pairing authentication in the
Bluetooth protocol could allow an unauthenticated user to complete
authentication without pairing credentials via adjacent access. A
physically proximate attacker could use this to impersonate a previously
paired Bluetooth device. (CVE-2020-10135)
Jay Shin discovered that the ext4 file system implementation in the Linux
kernel did not properly handle directory access with broken indexing,
leading to an out-of-bounds read vulnerability. A local attacker could use
this to cause a denial of service (system crash). (CVE-2020-14314)
It was discovered that the block layer implementation in the Linux kernel
did not properly perform reference counting in some situations, leading to
a use-after-free vulnerability. A local attacker could use this to cause a
denial of service (system crash). (CVE-2020-15436)
It was discovered that the serial port driver in the Linux kernel did not
properly initialize a pointer in some situations. A local attacker could
possibly use this to cause a denial of service (system crash).
(CVE-2020-15437)
Andy Nguyen discovered that the Bluetooth HCI event packet parser in the
Linux kernel did not properly handle event advertisements of certain sizes,
leading to a heap-based buffer overflow. A physically proximate remote
attacker could use this to cause a denial of service (system crash) or
possibly execute arbitrary code. (CVE-2020-24490)
It was discovered that the NFS client implementation in the Linux kernel
did not properly perform bounds checking before copying security labels in
some situations. A local attacker could use this to cause a denial of
service (system crash) or possibly execute arbitrary code. (CVE-2020-25212)
It was discovered that the Rados block device (rbd) driver in the Linux
kernel did not properly perform privilege checks for access to rbd devices
in some situations. A local attacker could use this to map or unmap rbd
block devices. (CVE-2020-25284)
It was discovered that the block layer subsystem in the Linux kernel did
not properly handle zero-length requests. A local attacker could use this
to cause a denial of service. (CVE-2020-25641)
It was discovered that the HDLC PPP implementation in the Linux kernel did
not properly validate input in some situations. A local attacker could use
this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2020-25643)
Kiyin (尹亮) discovered that the perf subsystem in the Linux kernel did
not properly deallocate memory in some situations. A privileged attacker
could use this to cause a denial of service (kernel memory exhaustion).
(CVE-2020-25704)
It was discovered that the KVM hypervisor in the Linux kernel did not
properly handle interrupts in certain situations. A local attacker in a
guest VM could possibly use this to cause a denial of service (host system
crash). (CVE-2020-27152)
It was discovered that the jfs file system implementation in the Linux
kernel contained an out-of-bounds read vulnerability. A local attacker
could use this to possibly cause a denial of service (system crash).
(CVE-2020-27815)
It was discovered that an information leak existed in the syscall
implementation in the Linux kernel on 32 bit systems. A local attacker
could use this to expose sensitive information (kernel memory).
(CVE-2020-28588)
It was discovered that the framebuffer implementation in the Linux kernel
did not properly perform range checks in certain situations. A local
attacker could use this to expose sensitive information (kernel memory).
(CVE-2020-28915)
Jann Horn discovered a race condition in the copy-on-write implementation
in the Linux kernel when handling hugepages. A local attacker could use
this to gain unintended write access to read-only memory pages.
(CVE-2020-29368)
Jann Horn discovered that the mmap implementation in the Linux kernel
contained a race condition when handling munmap() operations, 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.
(CVE-2020-29369)
Jann Horn discovered that the romfs file system in the Linux kernel did not
properly validate file system meta-data, leading to an out-of-bounds read.
An attacker could use this to construct a malicious romfs image that, when
mounted, exposed sensitive information (kernel memory). (CVE-2020-29371)
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)
It was discovered that a race condition existed that caused the Linux
kernel to not properly restrict exit signal delivery. A local attacker
could possibly use this to send signals to arbitrary processes.
(CVE-2020-35508)
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.