[PATCH 5.18 142/231] KVM: x86: Fully initialize struct kvm_lapic_irq in kvm_pv_kick_cpu_op()

Greg Kroah-Hartman
2022-07-19T13:02:26Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

[ Upstream commit 8a414f943f8b5f94bbaafdec863d6f3dbef33f8a ]

'vector' and 'trig_mode' fields of 'struct kvm_lapic_irq' are left
uninitialized in kvm_pv_kick_cpu_op(). While these fields are normally
not needed for APIC_DM_REMRD, they're still referenced by
__apic_accept_irq() for trace_kvm_apic_accept_irq(). Fully initialize
the structure to avoid consuming random stack memory.

Fixes: a183b638b61c ("KVM: x86: make apic_accept_irq tracepoint more generic")
Reported-by: syzbot+d6caa905917d353f0d07@syzkaller.appspotmail.com
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220708125147.593975-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/x86.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 558d1f2ab5b4..828f5cf1af45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9074,15 +9074,17 @@ static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr,
*/
static void kvm_pv_kick_cpu_op(struct kvm *kvm, int apicid)
{
- struct kvm_lapic_irq lapic_irq;
-
- lapic_irq.shorthand = APIC_DEST_NOSHORT;
- lapic_irq.dest_mode = APIC_DEST_PHYSICAL;
- lapic_irq.level = 0;
- lapic_irq.dest_id = apicid;
- lapic_irq.msi_redir_hint = false;
+ /*
+ * All other fields are unused for APIC_DM_REMRD, but may be consumed by
+ * common code, e.g. for tracing. Defer initialization to the compiler.
+ */
+ struct kvm_lapic_irq lapic_irq = {
+ .delivery_mode = APIC_DM_REMRD,
+ .dest_mode = APIC_DEST_PHYSICAL,
+ .shorthand = APIC_DEST_NOSHORT,
+ .dest_id = apicid,
+ };

- lapic_irq.delivery_mode = APIC_DM_REMRD;
kvm_irq_delivery_to_apic(kvm, NULL, &lapic_irq, NULL);
}

--
2.35.1