From c8cf86becc57da722dcd62c1aef21d163a3dd1a9 Mon Sep 17 00:00:00 2001
From: Eduardo Habkost <ehabkost@redhat.com>
Date: Fri, 16 Oct 2009 16:24:38 -0300
Subject: [PATCH] kvm: fix kvm_arch_save_regs() potential stack corruption

RH-Author: Eduardo Habkost <ehabkost@redhat.com>
Message-id: <20091014184927.GS24126@blackpad.lan.raisama.net>
Patchwork-id: 3592
O-Subject: [RHEL-5.5 KVM PATCH] kvm: fix kvm_arch_save_regs() potential stack
	corruption
Bugzilla: 528917
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=528917

A new register was added to the load/save list on commit
d283d5a65a2bdcc570065267be21848bd6fe3d78, but MSR_COUNT was not updated, leading
to potential stack corruption on kvm_arch_save_regs().

The following registers are saved by kvm_arch_save_regs():

 1) MSR_IA32_SYSENTER_CS
 2) MSR_IA32_SYSENTER_ESP
 3) MSR_IA32_SYSENTER_EIP
 4) MSR_STAR
 5) MSR_IA32_TSC
 6) MSR_VM_HSAVE_PA
 7) MSR_CSTAR (x86_64 only)
 8) MSR_KERNELGSBASE (x86_64 only)
 9) MSR_FMASK (x86_64 only)
10) MSR_LSTAR (x86_64 only)

Upstream status: submitted: http://marc.info/?l=kvm&m=125554346023751

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/qemu-kvm-x86.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/qemu-kvm-x86.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/qemu/qemu-kvm-x86.c b/qemu/qemu-kvm-x86.c
index 5be7004..e95c489 100644
--- a/qemu/qemu-kvm-x86.c
+++ b/qemu/qemu-kvm-x86.c
@@ -111,9 +111,9 @@ static int get_msr_entry(struct kvm_msr_entry *entry, CPUState *env)
 }
 
 #ifdef TARGET_X86_64
-#define MSR_COUNT 9
+#define MSR_COUNT 10
 #else
-#define MSR_COUNT 5
+#define MSR_COUNT 6
 #endif
 
 static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs)
@@ -255,6 +255,7 @@ void kvm_arch_load_regs(CPUState *env)
 
     /* msrs */
     n = 0;
+    /* Remember to increase MSR_COUNT if you add new registers below */
     set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_CS,  env->sysenter_cs);
     set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_ESP, env->sysenter_esp);
     set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_EIP, env->sysenter_eip);
@@ -429,6 +430,7 @@ void kvm_arch_save_regs(CPUState *env)
 
     /* msrs */
     n = 0;
+    /* Remember to increase MSR_COUNT if you add new registers below */
     msrs[n++].index = MSR_IA32_SYSENTER_CS;
     msrs[n++].index = MSR_IA32_SYSENTER_ESP;
     msrs[n++].index = MSR_IA32_SYSENTER_EIP;
-- 
1.6.3.rc4.29.g8146