From: Thomas Huth Date: Thu, 12 Sep 2019 11:54:38 +0000 (+0200) Subject: KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=fd1b7efe8e04ef259e7beb2f68af8d4f7a7e9d8e;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl commit 53936b5bf35e140ae27e4bbf0447a61063f400da upstream. When the userspace program runs the KVM_S390_INTERRUPT ioctl to inject an interrupt, we convert them from the legacy struct kvm_s390_interrupt to the new struct kvm_s390_irq via the s390int_to_s390irq() function. However, this function does not take care of all types of interrupts that we can inject into the guest later (see do_inject_vcpu()). Since we do not clear out the s390irq values before calling s390int_to_s390irq(), there is a chance that we copy random data from the kernel stack which could be leaked to the userspace later. Specifically, the problem exists with the KVM_S390_INT_PFAULT_INIT interrupt: s390int_to_s390irq() does not handle it, and the function __inject_pfault_init() later copies irq->u.ext which contains the random kernel stack data. This data can then be leaked either to the guest memory in __deliver_pfault_init(), or the userspace might retrieve it directly with the KVM_S390_GET_IRQ_STATE ioctl. Fix it by handling that interrupt type in s390int_to_s390irq(), too, and by making sure that the s390irq struct is properly pre-initialized. And while we're at it, make sure that s390int_to_s390irq() now directly returns -EINVAL for unknown interrupt types, so that we immediately get a proper error code in case we add more interrupt types to do_inject_vcpu() without updating s390int_to_s390irq() sometime in the future. Cc: stable@vger.kernel.org Reviewed-by: David Hildenbrand Reviewed-by: Christian Borntraeger Reviewed-by: Janosch Frank Signed-off-by: Thomas Huth Link: https://lore.kernel.org/kvm/20190912115438.25761-1-thuth@redhat.com Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 5185be314661..28f3796d23c8 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -1701,6 +1701,16 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int, case KVM_S390_MCHK: irq->u.mchk.mcic = s390int->parm64; break; + case KVM_S390_INT_PFAULT_INIT: + irq->u.ext.ext_params = s390int->parm; + irq->u.ext.ext_params2 = s390int->parm64; + break; + case KVM_S390_RESTART: + case KVM_S390_INT_CLOCK_COMP: + case KVM_S390_INT_CPU_TIMER: + break; + default: + return -EINVAL; } return 0; } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 70a446ec347d..a27fb640adbe 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3730,7 +3730,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, } case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; - struct kvm_s390_irq s390irq; + struct kvm_s390_irq s390irq = {}; r = -EFAULT; if (copy_from_user(&s390int, argp, sizeof(s390int)))