MGASA-2022-0279

This kernel-linus update is based on upstream 5.15.58 and fixes at least the following security issues:

Kernel lockdown bypass when UEFI secure boot is disabled / unavailable and IMA appraisal is enabled (CVE-2022-21505).

Aliases in the branch predictor may cause some AMD processors to predict the wrong branch type potentially leading to information disclosure (CVE-2022-23825).

Mis-trained branch predictions for return instructions may allow arbitrary speculative code execution under certain microarchitecture-dependent conditions (CVE-2022-29900, RetBleed).

Intel microprocessor generations 6 to 8 are affected by a new Spectre variant that is able to bypass their retpoline mitigation in the kernel to leak arbitrary data. An attacker with unprivileged user access can hijack return instructions to achieve arbitrary speculative code execution under certain microarchitecture-dependent conditions (CVE-2022-29901).

The Linux kernel before 5.18.13 lacks a certain clear operation for the block starting symbol (.bss). This allows Xen PV guest OS users to cause a denial of service or gain privileges (CVE-2022-36123).

An issue was discovered in the Linux kernel through 5.18.14. xfrmexpandpolicies in net/xfrm/xfrm_policy.c can cause a refcount to be dropped twice (CVE-2022-36879).

For other upstream fixes, see the referenced changelogs.