When cleaning up a UCONTROL VM, sca_clear_ext_call() will touch memory outside of the allocated ESCA block, and UCONTROL VMs don't even use ESCA. Fix by not touching ESCA for UCONTROL VMs, and fence the KVM_S390_INTERRUPT ioctl altogether. Opportunistically add checks in sca_ext_call_pending() and sca_inject_ext_call() to make sure UCONTROL VMs won't call those functions ever. Signed-off-by: Claudio Imbrenda Fixes: 7d43bafcff17 ("KVM: s390: Make provisions for ESCA utilization") --- arch/s390/kvm/interrupt.c | 19 ++++++++++++++----- arch/s390/kvm/kvm-s390.c | 3 +++ 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 2acdff130fa6..6013f28e3461 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -45,13 +45,16 @@ static struct kvm_s390_gib *gib; static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) { struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl; + union esca_sigp_ctrl sigp_ctrl; if (!kvm_s390_test_cpuflags(vcpu, CPUSTAT_ECALL_PEND)) return 0; + if (KVM_BUG_ON(kvm_is_ucontrol(vcpu->kvm), vcpu->kvm)) + return -EINVAL; BUG_ON(!kvm_s390_use_sca_entries()); + sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl; if (src_id) *src_id = sigp_ctrl.scn; @@ -60,13 +63,16 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) { - struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; union esca_sigp_ctrl old_val, new_val = {.scn = src_id, .c = 1}; + struct esca_block *sca = vcpu->kvm->arch.sca; + union esca_sigp_ctrl *sigp_ctrl; int expect, rc; BUG_ON(!kvm_s390_use_sca_entries()); + if (KVM_BUG_ON(kvm_is_ucontrol(vcpu->kvm), vcpu->kvm)) + return -EINVAL; + sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; old_val = READ_ONCE(*sigp_ctrl); old_val.c = 0; @@ -84,10 +90,13 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) static void sca_clear_ext_call(struct kvm_vcpu *vcpu) { struct esca_block *sca = vcpu->kvm->arch.sca; - union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; + union esca_sigp_ctrl *sigp_ctrl; - if (!kvm_s390_use_sca_entries() || !vcpu->arch.initialized) + if (!kvm_s390_use_sca_entries() || !vcpu->arch.initialized || kvm_is_ucontrol(vcpu->kvm)) return; + + /* Initialize after the above check, to prevent going out of bounds */ + sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl; kvm_s390_clear_cpuflags(vcpu, CPUSTAT_ECALL_PEND); WRITE_ONCE(sigp_ctrl->value, 0); diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 58cec3703c2d..19ce7ebb83c5 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2934,6 +2934,9 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; + r = -EINVAL; + if (kvm_is_ucontrol(kvm)) + break; r = -EFAULT; if (copy_from_user(&s390int, argp, sizeof(s390int))) break; -- 2.55.0