ext4_protect_reserved_inode in fs/ext4/block_validity.c in the Linux kernel through 5.5.3 allows attackers to cause a denial of service (soft lockup) via a crafted journal size.

Affected: Ubuntu:16.04:LTS: linux-hwe, Ubuntu:18.04:LTS: linux

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)