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authorNadav Amit <namit@cs.technion.ac.il>2014-06-15 16:12:59 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-05 16:28:35 -0700
commit8277c1d67e4c273858e5a423a9d091074056cc06 (patch)
tree689f327f64952cab2811e8661ac1680c349197e1 /arch
parent68344064b7c978712e32448d03935ad1ac6d75cd (diff)
KVM: x86: Inter-privilege level ret emulation is not implemeneted
commit 9e8919ae793f4edfaa29694a70f71a515ae9942a upstream. Return unhandlable error on inter-privilege level ret instruction. This is since the current emulation does not check the privilege level correctly when loading the CS, and does not pop RSP/SS as needed. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/emulate.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5484d54582ca..fb3fddc322f8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2209,6 +2209,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
{
int rc;
unsigned long cs;
+ int cpl = ctxt->ops->cpl(ctxt);
rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes);
if (rc != X86EMUL_CONTINUE)
@@ -2218,6 +2219,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
rc = emulate_pop(ctxt, &cs, ctxt->op_bytes);
if (rc != X86EMUL_CONTINUE)
return rc;
+ /* Outer-privilege level return is not implemented */
+ if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)
+ return X86EMUL_UNHANDLEABLE;
rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS);
return rc;
}