| Message ID | 20130628101718.GC25199@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@vger.kernel.org # 3.9+ > Reported-by: Stefan Pietsch <stefan.pietsch@lsexperts.de> > Tested-by: Stefan Pietsch <stefan.pietsch@lsexperts.de> > Signed-off-by: Gleb Natapov <gleb@redhat.com> > > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 02, 2013 at 10:15:54AM +0200, Paolo Bonzini wrote: > 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@vger.kernel.org # 3.9+ > > Reported-by: Stefan Pietsch <stefan.pietsch@lsexperts.de> > > Tested-by: Stefan Pietsch <stefan.pietsch@lsexperts.de> > > Signed-off-by: Gleb Natapov <gleb@redhat.com> > > > > 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. > It affects people so lets target it to 3.10/3.9-stable. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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)