kvm reloads the host's fs and gs blindly, however the underlying segment
descriptors may be invalid due to the user modifying the ldt after loading
them.
Fix by using the safe accessors (loadsegment() and load_gs_index()) instead
of home grown unsafe versions.
This is CVE-2010-3698.
KVM-Stable-Tag.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
return (struct kvm_mmu_page *)page_private(page);
}
return (struct kvm_mmu_page *)page_private(page);
}
-static inline u16 kvm_read_fs(void)
-{
- u16 seg;
- asm("mov %%fs, %0" : "=g"(seg));
- return seg;
-}
-
-static inline u16 kvm_read_gs(void)
-{
- u16 seg;
- asm("mov %%gs, %0" : "=g"(seg));
- return seg;
-}
-
static inline u16 kvm_read_ldt(void)
{
u16 ldt;
static inline u16 kvm_read_ldt(void)
{
u16 ldt;
-static inline void kvm_load_fs(u16 sel)
-{
- asm("mov %0, %%fs" : : "rm"(sel));
-}
-
-static inline void kvm_load_gs(u16 sel)
-{
- asm("mov %0, %%gs" : : "rm"(sel));
-}
-
static inline void kvm_load_ldt(u16 sel)
{
asm("lldt %0" : : "rm"(sel));
static inline void kvm_load_ldt(u16 sel)
{
asm("lldt %0" : : "rm"(sel));
sync_lapic_to_cr8(vcpu);
save_host_msrs(vcpu);
sync_lapic_to_cr8(vcpu);
save_host_msrs(vcpu);
- fs_selector = kvm_read_fs();
- gs_selector = kvm_read_gs();
+ savesegment(fs, fs_selector);
+ savesegment(gs, gs_selector);
ldt_selector = kvm_read_ldt();
svm->vmcb->save.cr2 = vcpu->arch.cr2;
/* required for live migration with NPT */
ldt_selector = kvm_read_ldt();
svm->vmcb->save.cr2 = vcpu->arch.cr2;
/* required for live migration with NPT */
vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
- kvm_load_fs(fs_selector);
- kvm_load_gs(gs_selector);
- kvm_load_ldt(ldt_selector);
+ loadsegment(fs, fs_selector);
+#ifdef CONFIG_X86_64
+ load_gs_index(gs_selector);
+ wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
+#else
+ loadsegment(gs, gs_selector);
+#endif
+ kvm_load_ldt(ldt_selector);
*/
vmx->host_state.ldt_sel = kvm_read_ldt();
vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;
*/
vmx->host_state.ldt_sel = kvm_read_ldt();
vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;
- vmx->host_state.fs_sel = kvm_read_fs();
+ savesegment(fs, vmx->host_state.fs_sel);
if (!(vmx->host_state.fs_sel & 7)) {
vmcs_write16(HOST_FS_SELECTOR, vmx->host_state.fs_sel);
vmx->host_state.fs_reload_needed = 0;
if (!(vmx->host_state.fs_sel & 7)) {
vmcs_write16(HOST_FS_SELECTOR, vmx->host_state.fs_sel);
vmx->host_state.fs_reload_needed = 0;
vmcs_write16(HOST_FS_SELECTOR, 0);
vmx->host_state.fs_reload_needed = 1;
}
vmcs_write16(HOST_FS_SELECTOR, 0);
vmx->host_state.fs_reload_needed = 1;
}
- vmx->host_state.gs_sel = kvm_read_gs();
+ savesegment(gs, vmx->host_state.gs_sel);
if (!(vmx->host_state.gs_sel & 7))
vmcs_write16(HOST_GS_SELECTOR, vmx->host_state.gs_sel);
else {
if (!(vmx->host_state.gs_sel & 7))
vmcs_write16(HOST_GS_SELECTOR, vmx->host_state.gs_sel);
else {
static void __vmx_load_host_state(struct vcpu_vmx *vmx)
{
static void __vmx_load_host_state(struct vcpu_vmx *vmx)
{
if (!vmx->host_state.loaded)
return;
++vmx->vcpu.stat.host_state_reload;
vmx->host_state.loaded = 0;
if (vmx->host_state.fs_reload_needed)
if (!vmx->host_state.loaded)
return;
++vmx->vcpu.stat.host_state_reload;
vmx->host_state.loaded = 0;
if (vmx->host_state.fs_reload_needed)
- kvm_load_fs(vmx->host_state.fs_sel);
+ loadsegment(fs, vmx->host_state.fs_sel);
if (vmx->host_state.gs_ldt_reload_needed) {
kvm_load_ldt(vmx->host_state.ldt_sel);
if (vmx->host_state.gs_ldt_reload_needed) {
kvm_load_ldt(vmx->host_state.ldt_sel);
- /*
- * If we have to reload gs, we must take care to
- * preserve our gs base.
- */
- local_irq_save(flags);
- kvm_load_gs(vmx->host_state.gs_sel);
- wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
+ load_gs_index(vmx->host_state.gs_sel);
+ wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
+#else
+ loadsegment(gs, vmx->host_state.gs_sel);
- local_irq_restore(flags);
}
reload_tss();
#ifdef CONFIG_X86_64
}
reload_tss();
#ifdef CONFIG_X86_64
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
- vmcs_write16(HOST_FS_SELECTOR, kvm_read_fs()); /* 22.2.4 */
- vmcs_write16(HOST_GS_SELECTOR, kvm_read_gs()); /* 22.2.4 */
+ vmcs_write16(HOST_FS_SELECTOR, 0); /* 22.2.4 */
+ vmcs_write16(HOST_GS_SELECTOR, 0); /* 22.2.4 */
vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
#ifdef CONFIG_X86_64
rdmsrl(MSR_FS_BASE, a);
vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
#ifdef CONFIG_X86_64
rdmsrl(MSR_FS_BASE, a);