From 89efbed02cfd7e9ce3324de0b44a70ee1c716fac Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Thu, 20 Dec 2012 16:57:44 +0200 Subject: [PATCH] KVM: VMX: make rmode_segment_valid() more strict. Currently it allows entering vm86 mode if segment limit is greater than 0xffff and db bit is set. Both of those can cause incorrect execution of instruction by cpu since in vm86 mode limit will be set to 0xffff and db will be forced to 0. Signed-off-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/vmx.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 23d5aec..7ebcac2 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3341,15 +3341,13 @@ static bool rmode_segment_valid(struct kvm_vcpu *vcpu, int seg) vmx_get_segment(vcpu, &var, seg); var.dpl = 0x3; - var.g = 0; - var.db = 0; if (seg == VCPU_SREG_CS) var.type = 0x3; ar = vmx_segment_access_rights(&var); if (var.base != (var.selector << 4)) return false; - if (var.limit < 0xffff) + if (var.limit != 0xffff) return false; if (ar != 0xf3) return false; -- 2.7.4