SB2021012641 - Amazon Linux AMI update for kernel
Published: January 26, 2021 Updated: August 9, 2024
Breakdown by Severity
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- Critical
Description
This security bulletin contains information about 8 secuirty vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2019-19813)
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in __mutex_lock in kernel/locking/mutex.c. This is related to mutex_can_spin_on_owner in kernel/locking/mutex.c, __btrfs_qgroup_free_meta in fs/btrfs/qgroup.c, and btrfs_insert_delayed_items in fs/btrfs/delayed-inode.c.
2) Out-of-bounds write (CVE-ID: CVE-2019-19816)
The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.
In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image and performing some operations can cause slab-out-of-bounds write access in __btrfs_map_block in fs/btrfs/volumes.c, because a value of 1 for the number of data stripes is mishandled.
3) 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.
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) 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.
6) Unchecked Return Value (CVE-ID: CVE-2020-29569)
The vulnerability allows a local user to compromise the target system.
The vulnerability exists due to an unchecked return value. A local user can cause a denial of service (DoS) condition, leading to privilege escalation and information leaks.
7) 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.
8) 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.