Il 28/06/2013 12:17, Gleb Natapov ha scritto: > Some userspaces do not preserve unusable property. Since usable > segment has to be present according to VMX spec we can use present > property to amend userspace bug by making unusable segment always > nonpresent. vmx_segment_access_rights() already marks nonpresent segment > as unusable. > > Cc: stable@xxxxxxxxxxxxxxx # 3.9+ > Reported-by: Stefan Pietsch <stefan.pietsch@xxxxxxxxxxxx> > Tested-by: Stefan Pietsch <stefan.pietsch@xxxxxxxxxxxx> > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx> > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 260a919..5402c94 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3399,15 +3399,22 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu, > var->limit = vmx_read_guest_seg_limit(vmx, seg); > var->selector = vmx_read_guest_seg_selector(vmx, seg); > ar = vmx_read_guest_seg_ar(vmx, seg); > + var->unusable = (ar >> 16) & 1; > var->type = ar & 15; > var->s = (ar >> 4) & 1; > var->dpl = (ar >> 5) & 3; > - var->present = (ar >> 7) & 1; > + /* > + * Some userspaces do not preserve unusable property. Since usable > + * segment has to be present according to VMX spec we can use present > + * property to amend userspace bug by making unusable segment always > + * nonpresent. vmx_segment_access_rights() already marks nonpresent > + * segment as unusable. > + */ > + var->present = !var->unusable; > var->avl = (ar >> 12) & 1; > var->l = (ar >> 13) & 1; > var->db = (ar >> 14) & 1; > var->g = (ar >> 15) & 1; > - var->unusable = (ar >> 16) & 1; > } > > static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg) > -- > Gleb. > Looks good, but for now I'm leaving it out of the 3.11 pull request. Applied to queue. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
