[USN-4752-1] Linux kernel (OEM) vulnerabilities

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-4752-1
February 25, 2021

linux-oem-5.6 vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- 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 LTS:
  linux-image-5.6.0-1048-oem      5.6.0-1048.52
  linux-image-oem-20.04           5.6.0.1048.44

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:
  https://usn.ubuntu.com/4752-1
  CVE-2020-10135, CVE-2020-14314, CVE-2020-15436, CVE-2020-15437,
  CVE-2020-24490, CVE-2020-25212, CVE-2020-25284, CVE-2020-25641,
  CVE-2020-25643, CVE-2020-25704, CVE-2020-27152, CVE-2020-27815,
  CVE-2020-28588, CVE-2020-28915, CVE-2020-29368, CVE-2020-29369,
  CVE-2020-29371, CVE-2020-29660, CVE-2020-29661, CVE-2020-35508

Package Information:
  https://launchpad.net/ubuntu/+source/linux-oem-5.6/5.6.0-1048.52

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