In the Linux kernel, the following vulnerability has been resolved: kvm: s390: Reject memory region operations for ucontrol VMs This change rejects the KVMSETUSERMEMORYREGION and KVMSETUSERMEMORYREGION2 ioctls when called on a ucontrol VM. This is necessary since ucontrol VMs have kvm->arch.gmap set to 0 and would thus result in a null pointer dereference further in. Memory management needs to be performed in userspace and using the ioctls KVMS390UCASMAP and KVMS390UCASUNMAP. Also improve s390 specific documentation for KVMSETUSERMEMORYREGION and KVMSETUSERMEMORYREGION2. [frankja@linux.ibm.com: commit message spelling fix, subject prefix fix]