This is CVE-2017-8106. ** CVE added: http://www.cve.mitre.org/cgi- bin/cvename.cgi?name=2017-8106
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1678676 Title: linux_3.13.0-*.*: nVMX: Check current_vmcs12 before accessing in handle_invept() Status in linux package in Ubuntu: Invalid Status in linux source package in Trusty: Triaged Bug description: KVM in linux 3.11 - 3.14 (including ubuntu 14.04 linux <= 3.13.0-113.160) has a flaw in INVEPT emulation that could crash the host. [ 1046.384746] BUG: unable to handle kernel NULL pointer dereference at 0000000000000070 [ 1046.387386] IP: [<ffffffffa05b3ca3>] handle_invept+0x123/0x170 [kvm_intel] [ 1046.389577] PGD 0 [ 1046.390273] Oops: 0000 [#1] SMP (tested with Ubuntu 14.04 linux-image-3.13.0-113-generic) The host KVM touches NULL pointer (vmx->nested.current_vmcs12) when a (crafted or buggy) guest issues a single-context INVEPT instruction *without* VMPTRLD like this: kvm_cpu_vmxon(phys_addr); ept_sync_context(0); (requires nested EPT; full linux kernel module code attached) This code is introduced in upstream commit bfd0a56b90005f8c8a004baf407ad90045c2b11e (nEPT: Nested INVEPT) and removed in 4b855078601fc422dbac3059f2215e776f49780f (KVM: nVMX: Don't advertise single context invalidation for invept). Therefore there should be two ways to fix this. a. pullup bfd0a56b90005f (and 45e11817d5703e) b. check current_vmcs12 before accessing for minimal fix: diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index d9e567f..d785e9c 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -6391,6 +6391,8 @@ static int handle_invept(struct kvm_vcpu *vcpu) switch (type) { case VMX_EPT_EXTENT_CONTEXT: + if (to_vmx(vcpu)->nested.current_vmptr == -1ull) + break; if ((operand.eptp & eptp_mask) != (nested_ept_get_cr3(vcpu) & eptp_mask)) break; To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1678676/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
