From 0307fe931f450a3de31a9e59895f810bae2f89b9 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Thu, 4 Nov 2010 16:38:10 -0200
Subject: [PATCH] KVM: x86: fix information leak to userland

RH-Author: Marcelo Tosatti <mtosatti@redhat.com>
Message-id: <20101104163810.GA25902@amt.cnet>
Patchwork-id: 13215
O-Subject: [RHEL5.4.z 5.5.z 5.6] KVM: x86: fix information leak to userland
Bugzilla: 649929
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Avi Kivity <avi@redhat.com>
RH-Acked-by: Gleb Natapov <gleb@redhat.com>

KVM: x86: fix information leak to userland

Structures kvm_vcpu_events, kvm_debugregs, kvm_pit_state2 and
kvm_clock_data are copied to userland with some padding and reserved
fields unitialized.  It leads to leaking of contents of kernel stack
memory.  We have to initialize them to zero.

In patch v1 Jan Kiszka suggested to fill reserved fields with zeros
instead of memset'ting the whole struct.  It makes sense as these
fields are explicitly marked as padding.  No more fields need zeroing.

KVM-Stable-Tag.
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
(upstream backport of commit 831d9d02f9522e739825a51a11e3bc5aa531a905)
BZ: 649832

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 arch/x86/kvm/x86.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9a613cb..0cafff6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1528,6 +1528,7 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 	events->exception.injected = vcpu->arch.exception.pending;
 	events->exception.nr = vcpu->arch.exception.nr;
 	events->exception.has_error_code = vcpu->arch.exception.has_error_code;
+	events->exception.pad = 0;
 	events->exception.error_code = vcpu->arch.exception.error_code;
 
 	events->interrupt.injected = vcpu->arch.interrupt.pending;
@@ -1537,10 +1538,12 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 	events->nmi.injected = vcpu->arch.nmi_injected;
 	events->nmi.pending = vcpu->arch.nmi_pending;
 	events->nmi.masked = kvm_x86_ops->get_nmi_mask(vcpu);
+	events->nmi.pad = 0;
 
 	events->sipi_vector = vcpu->arch.sipi_vector;
 
 	events->flags = 0;
+	memset(&events->reserved, 0, sizeof(events->reserved));
 
 	vcpu_put(vcpu);
 }
@@ -2176,6 +2179,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		now_ns = timespec_to_ns(&now);
 		user_ns.clock = kvm->arch.kvmclock_offset + now_ns;
 		user_ns.flags = 0;
+		memset(&user_ns.pad, 0, sizeof(user_ns.pad));
 
 		r = -EFAULT;
 		if (copy_to_user(argp, &user_ns, sizeof(user_ns)))
-- 
1.7.3.2