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KVM: nVMX: Trap unconditionally if msr bitmap access fails

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This avoids basing decisions on uninitialized variables, potentially
leaking kernel data to the L1 guest.

Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2013-02-14 19:46:27 +01:00 committed by Marcelo Tosatti
parent 908a7bdd6a
commit bd31a7f557
1 changed files with 2 additions and 1 deletions
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arch/x86/kvm/vmx.c
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@ -5985,7 +5985,8 @@ static bool nested_vmx_exit_handled_msr(struct kvm_vcpu *vcpu,
/* Then read the msr_index'th bit from this bitmap: */
if (msr_index < 1024*8) {
unsigned char b;
kvm_read_guest(vcpu->kvm, bitmap + msr_index/8, &b, 1);
if (kvm_read_guest(vcpu->kvm, bitmap + msr_index/8, &b, 1))
return 1;
return 1 & (b >> (msr_index & 7));
} else
return 1; /* let L1 handle the wrong parameter */