Several security issues were fixed in the Linux kernel.
Al Viro discovered that the vfs layer in the Linux kernel contained a use- 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-2020-8428)
6 April 2020
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in the Linux kernel.
Al Viro discovered that the vfs layer in the Linux kernel contained a use- 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-2020-8428)
Gustavo Romero and Paul Mackerras discovered that the KVM implementation in the Linux kernel for PowerPC processors did not properly keep guest state separate from host state. A local attacker in a KVM guest could use this to cause a denial of service (host system crash). (CVE-2020-8834)
Shijie Luo discovered that the ext4 file system implementation in the Linux kernel did not properly check for a too-large journal size. An attacker could use this to construct a malicious ext4 image that, when mounted, could cause a denial of service (soft lockup). (CVE-2020-8992)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
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.