From: Peter Shier Date: Thu, 11 Oct 2018 11:46:46 -0700 Subject: KVM: nVMX: unconditionally cancel preemption timer in free_nested (CVE-2019-7221) Origin: https://git.kernel.org/linus/ecec76885bcfe3294685dc363fd1273df0d5d65f Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-7221 Bugzilla: 1671904 There are multiple code paths where an hrtimer may have been started to emulate an L1 VMX preemption timer that can result in a call to free_nested without an intervening L2 exit where the hrtimer is normally cancelled. Unconditionally cancel in free_nested to cover all cases. Embargoed until Feb 7th 2019. Signed-off-by: Peter Shier Reported-by: Jim Mattson Reviewed-by: Jim Mattson Reported-by: Felix Wilhelm Cc: stable@kernel.org Message-Id: <20181011184646.154065-1-pshier@google.com> Signed-off-by: Paolo Bonzini [carnil: Backport to 4.19. Adjust filename to arch/x86/kvm/vmx/vmx.c as later refactoring moved nested code to dedicated files] --- --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8469,6 +8469,7 @@ static void free_nested(struct vcpu_vmx if (!vmx->nested.vmxon && !vmx->nested.smm.vmxon) return; + hrtimer_cancel(&vmx->nested.preemption_timer); vmx->nested.vmxon = false; vmx->nested.smm.vmxon = false; free_vpid(vmx->nested.vpid02);