SB2021022538 - Ubuntu update for linux

Description

This security bulletin contains information about 6 secuirty vulnerabilities.

1) Out-of-bounds read (CVE-ID: CVE-2020-27815)

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary condition in fs/jfs/jfs_dmap.c. A local user can trigger out-of-bounds read error and crash the kernel.

2) Race condition (CVE-ID: CVE-2020-29374)

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to a race condition in the mm/gup.c and mm/huge_memory.c in Linux kernel. A local user can exploit the race and gain unauthorized access to sensitive information.

3) Buffer overflow (CVE-ID: CVE-2020-29568)

The vulnerability allows a local authenticated user to a crash the entire system.

An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are processing watch events using a single thread. If the events are received faster than the thread is able to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable.

4) Buffer overflow (CVE-ID: CVE-2020-29568)

The vulnerability allows a local authenticated user to a crash the entire system.

An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are processing watch events using a single thread. If the events are received faster than the thread is able to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable.

5) Improper locking (CVE-ID: CVE-2020-29660)

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to double-locking error in drivers/tty/tty_io.c and drivers/tty/tty_jobctrl.c. An authenticated local user can exploit this vulnerability to perform a read-after-free attack against TIOCGSID and gain access to sensitive information.

6) Improper locking (CVE-ID: CVE-2020-29661)

The vulnerability allows a local user to perform a escalate privileges on the system.

The vulnerability exists due to locking error in the tty subsystem of the Linux kernel in drivers/tty/tty_jobctrl.c. An local user can exploit this vulnerability to trigger a use-after-free error against TIOCSPGRP and execute arbitrary code with elevated privileges.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-4748-1