Commit 7709b2c6 authored May 11, 2020 by Jim Mattson Committed by Greg Kroah-Hartman May 20, 2020

KVM: x86: Fix off-by-one error in kvm_vcpu_ioctl_x86_setup_mce



commit c4e0e4ab4cf3ec2b3f0b628ead108d677644ebd9 upstream.

Bank_num is a one-based count of banks, not a zero-based index. It
overflows the allocated space only when strictly greater than
KVM_MAX_MCE_BANKS.

Fixes: a9e38c3e ("KVM: x86: Catch potential overrun in MCE setup")
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Message-Id: <20200511225616.19557-1-jmattson@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 1c87f4f3

arch/x86/kvm/x86.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -3423,7 +3423,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
		unsigned bank_num = mcg_cap & 0xff, bank;

		r = -EINVAL;
		if (!bank_num \|\| bank_num >= KVM_MAX_MCE_BANKS)
		if (!bank_num \|\| bank_num > KVM_MAX_MCE_BANKS)
		goto out;
		if (mcg_cap & ~(kvm_mce_cap_supported \| 0xff \| 0xff0000))
		goto out;