From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [PATCH] KVM: x86: Fix TSS size check for 16-bit tasks Date: Mon, 22 Mar 2010 11:29:40 +0100 Message-ID: <4BA74694.2080300@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: kvm To: Avi Kivity , Marcelo Tosatti Return-path: Received: from thoth.sbs.de ([192.35.17.2]:20613 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753307Ab0CVK3x (ORCPT ); Mon, 22 Mar 2010 06:29:53 -0400 Sender: kvm-owner@vger.kernel.org List-ID: A 16-bit TSS is only 44 bytes long. So make sure to test for the correct size on task switch. Signed-off-by: Jan Kiszka --- This should be stable material as well. I can provide a patch that applies on .32 and .33, or what will be the procedure? arch/x86/kvm/emulate.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 266576c..f529f75 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2355,6 +2355,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, u16 old_tss_sel = ops->get_segment_selector(VCPU_SREG_TR, ctxt->vcpu); ulong old_tss_base = get_cached_descriptor_base(ctxt, ops, VCPU_SREG_TR); + u32 desc_limit; /* FIXME: old_tss_base == ~0 ? */ @@ -2375,7 +2376,10 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, } } - if (!next_tss_desc.p || desc_limit_scaled(&next_tss_desc) < 0x67) { + desc_limit = desc_limit_scaled(&next_tss_desc); + if (!next_tss_desc.p || + ((desc_limit < 0x67 && (next_tss_desc.type & 8)) || + desc_limit < 0x2c)) { kvm_queue_exception_e(ctxt->vcpu, TS_VECTOR, tss_selector & 0xfffc); return X86EMUL_PROPAGATE_FAULT;