From e8180dcaa8470ceca21109f143876fdcd9fe050a Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Thu, 9 May 2013 00:28:06 +0200 Subject: [PATCH] ARM: KVM: prevent NULL pointer dereferences with KVM VCPU ioctl Some ARM KVM VCPU ioctls require the vCPU to be properly initialized with the KVM_ARM_VCPU_INIT ioctl before being used with further requests. KVM_RUN checks whether this initialization has been done, but other ioctls do not. Namely KVM_GET_REG_LIST will dereference an array with index -1 without initialization and thus leads to a kernel oops. Fix this by adding checks before executing the ioctl handlers. [ Removed superflous comment from static function - Christoffer ] Changes from v1: * moved check into a static function with a meaningful name Signed-off-by: Andre Przywara Signed-off-by: Christoffer Dall --- arch/arm/kvm/arm.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 37d216d814cd..ef1703b9587b 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -492,6 +492,11 @@ static void vcpu_pause(struct kvm_vcpu *vcpu) wait_event_interruptible(*wq, !vcpu->arch.pause); } +static int kvm_vcpu_initialized(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.target >= 0; +} + /** * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code * @vcpu: The VCPU pointer @@ -508,8 +513,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) int ret; sigset_t sigsaved; - /* Make sure they initialize the vcpu with KVM_ARM_VCPU_INIT */ - if (unlikely(vcpu->arch.target < 0)) + if (unlikely(!kvm_vcpu_initialized(vcpu))) return -ENOEXEC; ret = kvm_vcpu_first_run_init(vcpu); @@ -710,6 +714,10 @@ long kvm_arch_vcpu_ioctl(struct file *filp, case KVM_SET_ONE_REG: case KVM_GET_ONE_REG: { struct kvm_one_reg reg; + + if (unlikely(!kvm_vcpu_initialized(vcpu))) + return -ENOEXEC; + if (copy_from_user(®, argp, sizeof(reg))) return -EFAULT; if (ioctl == KVM_SET_ONE_REG) @@ -722,6 +730,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp, struct kvm_reg_list reg_list; unsigned n; + if (unlikely(!kvm_vcpu_initialized(vcpu))) + return -ENOEXEC; + if (copy_from_user(®_list, user_list, sizeof(reg_list))) return -EFAULT; n = reg_list.n; -- 2.20.1