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From: Jan Kiszka <jan.kiszka@web.de>
To: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm <kvm@vger.kernel.org>
Subject: [PATCH v2] KVM: x86: Fix TSS size check for 16-bit tasks
Date: Tue, 23 Mar 2010 12:25:44 +0100	[thread overview]
Message-ID: <4BA8A538.8040107@web.de> (raw)
In-Reply-To: <4BA74694.2080300@siemens.com>

From: Jan Kiszka <jan.kiszka@siemens.com>

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 <jan.kiszka@siemens.com>
---

Changes in v2:
 - fixed off-by-one in 16-bit limit

 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..ab3fff5 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 < 0x2b)) {
 		kvm_queue_exception_e(ctxt->vcpu, TS_VECTOR,
 				      tss_selector & 0xfffc);
 		return X86EMUL_PROPAGATE_FAULT;

  parent reply	other threads:[~2010-03-23 11:25 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-22 10:29 [PATCH] KVM: x86: Fix TSS size check for 16-bit tasks Jan Kiszka
2010-03-23 10:25 ` Avi Kivity
2010-03-23 10:42   ` Avi Kivity
2010-03-23 12:14     ` Jan Kiszka
2010-03-23 11:21   ` Jan Kiszka
2010-03-23 12:25     ` Avi Kivity
2010-03-23 11:25 ` Jan Kiszka [this message]
2010-03-23 12:35   ` [PATCH v2] " Avi Kivity

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