CVE-2026-89921

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

KVM: s390: Zero initialize data structures for inject_pfault_token

__kvm_inject_pfault_token() only sets .type and .u.ext.ext_params2 of the on-stack struct kvm_s390_irq but the full ext substructure is copied into the cpu local variable on inject. ext_params and pad contain stale stack values.

Interrupt delivery only uses ext_params2, so nothing leaks to the guest, but a host user can use the migration ioctls to get to the data.

Fix by zero-initializing the irq struct. Do the same for the inti data structure.