[PATCH 4.14 219/237] KVM: apic: avoid calculating pending eoi from an uninitialized val

Greg Kroah-Hartman
2020-02-27T14:32:46Z

From: Miaohe Lin <linmiaohe@huawei.com>

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>

---
arch/x86/kvm/lapic.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -566,9 +566,11 @@ static inline bool pv_eoi_enabled(struct
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;
}