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KVM: x86: Catch potential overrun in MCE setup 

We only allocate memory for 32 MCE banks (KVM_MAX_MCE_BANKS) but we
allow user space to fill up to 255 on setup (mcg_cap & 0xff), corrupting
kernel memory. Catch these overflows.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2009-10-23 09:37:00 +02:00 committed by Marcelo Tosatti
parent 51bb296b09
commit a9e38c3e01
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kvm/x86.c
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@ -1692,7 +1692,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
unsigned bank_num = mcg_cap & 0xff, bank; unsigned bank_num = mcg_cap & 0xff, bank;
r = -EINVAL; r = -EINVAL;
if (!bank_num) if (!bank_num || bank_num >= KVM_MAX_MCE_BANKS)
goto out; goto out;
if (mcg_cap & ~(KVM_MCE_CAP_SUPPORTED | 0xff | 0xff0000)) if (mcg_cap & ~(KVM_MCE_CAP_SUPPORTED | 0xff | 0xff0000))
goto out; goto out;