KVM: apic: avoid calculating pending eoi from an uninitialized val

BugLink: https://bugs.launchpad.net/bugs/1867837
commit 23520b2def95205f132e167cf5b25c609975e959 upstream.

When pv_eoi_get_user() fails, 'val' may remain uninitialized and the return
value of pv_eoi_get_pending() becomes random. Fix the issue by initializing
the variable.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 47cfcf51cec5d9da2ca6f99c668f032c30447b5a..363acc6702ee9fec713b40c3dff0c134a679ba7b 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -566,9 +566,11 @@ static inline bool pv_eoi_enabled(struct kvm_vcpu *vcpu)
 static bool pv_eoi_get_pending(struct kvm_vcpu *vcpu)
 {
        u8 val;
-       if (pv_eoi_get_user(vcpu, &val) < 0)
+       if (pv_eoi_get_user(vcpu, &val) < 0) {
                apic_debug("Can't read EOI MSR value: 0x%llx\n",
                           (unsigned long long)vcpu->arch.pv_eoi.msr_val);
+               return false;
+       }
        return val & 0x1;
 }