From 3313bc4ee83c4e2870d8e83800c6064b0d215679 Mon Sep 17 00:00:00 2001 From: Nadav Amit Date: Thu, 25 Dec 2014 02:52:17 +0200 Subject: [PATCH] KVM: x86: pop sreg accesses only 2 bytes Although pop sreg updates RSP according to the operand size, only 2 bytes are read. The current behavior may result in incorrect #GP or #PF exceptions. Signed-off-by: Nadav Amit Signed-off-by: Paolo Bonzini --- arch/x86/kvm/emulate.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index feaba468cce6..abe95d2e6848 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1828,12 +1828,14 @@ static int em_pop_sreg(struct x86_emulate_ctxt *ctxt) unsigned long selector; int rc; - rc = emulate_pop(ctxt, &selector, ctxt->op_bytes); + rc = emulate_pop(ctxt, &selector, 2); if (rc != X86EMUL_CONTINUE) return rc; if (ctxt->modrm_reg == VCPU_SREG_SS) ctxt->interruptibility = KVM_X86_SHADOW_INT_MOV_SS; + if (ctxt->op_bytes > 2) + rsp_increment(ctxt, ctxt->op_bytes - 2); rc = load_segment_descriptor(ctxt, (u16)selector, seg); return rc; -- 2.20.1