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 8974884ef2ad..732c3f2f8ded 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8713,15 +8713,17 @@ static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr, */ static void kvm_pv_kick_cpu_op(struct kvm *kvm, unsigned long flags, 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); }