RHSA-2020:3273: Moderate: grub2 security and bug fix update

The grub2 packages provide version 2 of the Grand Unified Boot Loader (GRUB), a highly configurable and customizable boot loader with modular architecture. The packages support a variety of kernel formats, file systems, computer architectures, and hardware devices.<br>The shim package contains a first-stage UEFI boot loader that handles chaining to a trusted full boot loader under secure boot environments.<br>Security Fix(es):<br><li> grub2: Crafted grub.cfg file can lead to arbitrary code execution during boot process (CVE-2020-10713)</li> <li> grub2: grubmalloc does not validate allocation size allowing for arithmetic overflow and subsequent heap-based buffer overflow (CVE-2020-14308)</li> <li> grub2: Integer overflow in grubsquashreadsymlink may lead to heap-based buffer overflow (CVE-2020-14309)</li> <li> grub2: Integer overflow readsectionasstring may lead to heap-based buffer overflow (CVE-2020-14310)</li> <li> grub2: Integer overflow in grubext2readlink leads to heap-based buffer overflow (CVE-2020-14311)</li> <li> grub2: Fail kernel validation without shim protocol (CVE-2020-15705)</li> <li> grub2: Use-after-free redefining a function whilst the same function is already executing (CVE-2020-15706)</li> For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.<br>Bug Fix(es):<br><li> grub2 should get resynced with 7.8 branch (BZ#1861861)</li>