CVE-2026-89920

Summary

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

KVM: s390: Fix memory corruption by not reinjecting CK machine checks

Channel-subsystem damage machine checks are for the host channel subsystem. The guest channel subsystem is emulated in the userspace VMM. There is no point in forwarding such machine checks into the guest.

This also simplifies the machine check reinjection and avoids kfree of a stack variable as reported by sashiko. There might be still machine checks that have the ck bit set with another bit (like instruction damage), mask out the CK bit in s390_backup_mcck_info(), like the CP and ED bits already are.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux4d62fcc0b692e3b4058d7d138114c27cd8b011f7 < 6ee52d3af2a1bf70349cf3f860933c8d221e229aaffected
LinuxLinux4d62fcc0b692e3b4058d7d138114c27cd8b011f7 < 7077ec953996acc04b49d1dfc43df1c1a2a74395affected
LinuxLinux4d62fcc0b692e3b4058d7d138114c27cd8b011f7 < 546dde823a36d7283dcf46127c2f3d093443860faffected
LinuxLinux4.13affected
LinuxLinux0 < 4.13unaffected
LinuxLinux6.18.51 <= 6.18.*unaffected
LinuxLinux7.2.5 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References