[patch 16/26] KVM: Prevent overflow in KVM_GET_SUPPORTED_CPUID

Greg KH
2009-10-09T23:17:34Z

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2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Avi Kivity <avi@redhat.com>

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kvm/x86.c | 2 ++
1 file changed, 2 insertions(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1429,6 +1429,8 @@ static int kvm_dev_ioctl_get_supported_c

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)