Amazon Linux 2 Security Advisory: ALAS-2021-1588
Advisory Release Date: 2021-01-25 23:09 Pacific
Advisory Updated Date: 2021-01-26 18:56 Pacific
FAQs regarding Amazon Linux ALAS/CVE Severity
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. (CVE-2019-19813)
A flaw was found in the implementation of the BTRFS file system code in the Linux kernel. An attacker, who is able to mount a crafted BTRFS filesystem and perform common filesystem operations, can possibly cause an out-of-bounds write to memory. This could lead to memory corruption or privilege escalation. (CVE-2019-19816)
This flaw is rated as having Moderate impact, there is a possibility that there is a write, although it is an uncontrolled write in a fixed offset from the current location. Also this issue is in non-default filesystem. (CVE-2020-27815)
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. ( cve-2020-29568)
An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback. (cve-2020-29569)
A locking inconsistency issue was discovered in the tty subsystem of the Linux kernel through 5.9.13. drivers/tty/tty_io.c and drivers/tty/tty_jobctrl.c may allow a read-after-free attack against TIOCGSID, aka CID-c8bcd9c5be24. (CVE-2020-29660)
A locking vulnerability was found in the tty subsystem of the Linux kernel in drivers/tty/tty_jobctrl.c. This flaw allows a local attacker to possibly corrupt memory or escalate privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. (CVE-2020-29661)
Affected Packages:
kernel
Note:
This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.
Issue Correction:
Run yum update kernel to update your system.
aarch64:
kernel-4.14.214-160.339.amzn2.aarch64
kernel-headers-4.14.214-160.339.amzn2.aarch64
kernel-debuginfo-common-aarch64-4.14.214-160.339.amzn2.aarch64
perf-4.14.214-160.339.amzn2.aarch64
perf-debuginfo-4.14.214-160.339.amzn2.aarch64
python-perf-4.14.214-160.339.amzn2.aarch64
python-perf-debuginfo-4.14.214-160.339.amzn2.aarch64
kernel-tools-4.14.214-160.339.amzn2.aarch64
kernel-tools-devel-4.14.214-160.339.amzn2.aarch64
kernel-tools-debuginfo-4.14.214-160.339.amzn2.aarch64
kernel-devel-4.14.214-160.339.amzn2.aarch64
kernel-debuginfo-4.14.214-160.339.amzn2.aarch64
i686:
kernel-headers-4.14.214-160.339.amzn2.i686
src:
kernel-4.14.214-160.339.amzn2.src
x86_64:
kernel-4.14.214-160.339.amzn2.x86_64
kernel-headers-4.14.214-160.339.amzn2.x86_64
kernel-debuginfo-common-x86_64-4.14.214-160.339.amzn2.x86_64
perf-4.14.214-160.339.amzn2.x86_64
perf-debuginfo-4.14.214-160.339.amzn2.x86_64
python-perf-4.14.214-160.339.amzn2.x86_64
python-perf-debuginfo-4.14.214-160.339.amzn2.x86_64
kernel-tools-4.14.214-160.339.amzn2.x86_64
kernel-tools-devel-4.14.214-160.339.amzn2.x86_64
kernel-tools-debuginfo-4.14.214-160.339.amzn2.x86_64
kernel-devel-4.14.214-160.339.amzn2.x86_64
kernel-debuginfo-4.14.214-160.339.amzn2.x86_64
kernel-livepatch-4.14.214-160.339-1.0-0.amzn2.x86_64