From 997138858db742022a87db305136f7e44d50c3b1 Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@redhat.com>
Date: Sun, 4 Oct 2009 16:45:13 +0200
Subject: [PATCH] KVM: Prevent overflow in KVM_GET_SUPPORTED_CPUID
 (CVE-2009-3638)

commit 6a54435560efdab1a08f429a954df4d6c740bddf upstream.

The number of entries is multiplied by the entry size, which can
overflow on 32-bit hosts.  Bound the entry count instead.

Reported-by: David Wagner <daw@cs.berkeley.edu>
Signed-off-by: Avi Kivity <avi@redhat.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 arch/x86/kvm/x86.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 60ebfd7eb0c..bf872f27289 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1223,6 +1223,8 @@ static int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
 
 	if (cpuid->nent < 1)
 		goto out;
+	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
+		cpuid->nent = KVM_MAX_CPUID_ENTRIES;
 	r = -ENOMEM;
 	cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
 	if (!cpuid_entries)
-- 
2.11.4.GIT