CVE-2023-52597

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: fix setting of fpc register

kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control

(fpc) register of a guest cpu. The new value is tested for validity by

temporarily loading it into the fpc register.

This may lead to corruption of the fpc register of the host process:

if an interrupt happens while the value is temporarily loaded into the fpc

register, and within interrupt context floating point or vector registers

are used, the current fp/vx registers are saved with save_fpu_regs()

assuming they belong to user space and will be loaded into fp/vx registers

when returning to user space.

test_fp_ctl() restores the original user space / host process fpc register

value, however it will be discarded, when returning to user space.

In result the host process will incorrectly continue to run with the value

that was supposed to be used for a guest cpu.

Fix this by simply removing the test. There

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References