[PATCH] KVM: X86: init irq->level in kvm_pv_kick_cpu_op

[PATCH] KVM: X86: init irq->level in kvm_pv_kick_cpu_op

[Longpeng(Mike)]

'lapic_irq' is a local variable and its 'level' field isn't
initialized, so 'level' is random, it doesn't matter but
makes UBSAN unhappy:

UBSAN: Undefined behaviour in .../lapic.c:...
load of value 10 is not a valid value for type '_Bool'
...
Call Trace:
 [<ffffffff81f030b6>] dump_stack+0x1e/0x20
 [<ffffffff81f03173>] ubsan_epilogue+0x12/0x55
 [<ffffffff81f03b96>] __ubsan_handle_load_invalid_value+0x118/0x162
 [<ffffffffa1575173>] kvm_apic_set_irq+0xc3/0xf0 [kvm]
 [<ffffffffa1575b20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm]
 [<ffffffffa15858ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm]
 [<ffffffffa1517f4e>] kvm_emulate_hypercall+0x62e/0x760 [kvm]
 [<ffffffffa113141a>] handle_vmcall+0x1a/0x30 [kvm_intel]
 [<ffffffffa114e592>] vmx_handle_exit+0x7a2/0x1fa0 [kvm_intel]
...

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
---
 arch/x86/kvm/x86.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6c97c82..b411f92 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6215,6 +6215,7 @@ static void kvm_pv_kick_cpu_op(struct kvm *kvm, unsigned long flags, int apicid)
 
 	lapic_irq.shorthand = 0;
 	lapic_irq.dest_mode = 0;
+	lapic_irq.level = 0;
 	lapic_irq.dest_id = apicid;
 	lapic_irq.msi_redir_hint = false;
 
-- 
1.8.3.1

Re: [PATCH] KVM: X86: init irq->level in kvm_pv_kick_cpu_op

[Paolo Bonzini]

On 02/08/2017 05:20, Longpeng(Mike) wrote:
> 'lapic_irq' is a local variable and its 'level' field isn't
> initialized, so 'level' is random, it doesn't matter but
> makes UBSAN unhappy:
> 
> UBSAN: Undefined behaviour in .../lapic.c:...
> load of value 10 is not a valid value for type '_Bool'
> ...
> Call Trace:
>  [<ffffffff81f030b6>] dump_stack+0x1e/0x20
>  [<ffffffff81f03173>] ubsan_epilogue+0x12/0x55
>  [<ffffffff81f03b96>] __ubsan_handle_load_invalid_value+0x118/0x162
>  [<ffffffffa1575173>] kvm_apic_set_irq+0xc3/0xf0 [kvm]
>  [<ffffffffa1575b20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm]
>  [<ffffffffa15858ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm]
>  [<ffffffffa1517f4e>] kvm_emulate_hypercall+0x62e/0x760 [kvm]
>  [<ffffffffa113141a>] handle_vmcall+0x1a/0x30 [kvm_intel]
>  [<ffffffffa114e592>] vmx_handle_exit+0x7a2/0x1fa0 [kvm_intel]
> ...
> 
> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
> ---
>  arch/x86/kvm/x86.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6c97c82..b411f92 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6215,6 +6215,7 @@ static void kvm_pv_kick_cpu_op(struct kvm *kvm, unsigned long flags, int apicid)
>  
>  	lapic_irq.shorthand = 0;
>  	lapic_irq.dest_mode = 0;
> +	lapic_irq.level = 0;
>  	lapic_irq.dest_id = apicid;
>  	lapic_irq.msi_redir_hint = false;

Looks good.  Thanks,

Paolo

Re: [PATCH] KVM: X86: init irq->level in kvm_pv_kick_cpu_op

[Radim Krčmář]

2017-08-02 11:20+0800, Longpeng(Mike):
> 'lapic_irq' is a local variable and its 'level' field isn't
> initialized, so 'level' is random, it doesn't matter but
> makes UBSAN unhappy:
> 
> UBSAN: Undefined behaviour in .../lapic.c:...
> load of value 10 is not a valid value for type '_Bool'
> ...
> Call Trace:
>  [<ffffffff81f030b6>] dump_stack+0x1e/0x20
>  [<ffffffff81f03173>] ubsan_epilogue+0x12/0x55
>  [<ffffffff81f03b96>] __ubsan_handle_load_invalid_value+0x118/0x162
>  [<ffffffffa1575173>] kvm_apic_set_irq+0xc3/0xf0 [kvm]
>  [<ffffffffa1575b20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm]
>  [<ffffffffa15858ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm]
>  [<ffffffffa1517f4e>] kvm_emulate_hypercall+0x62e/0x760 [kvm]
>  [<ffffffffa113141a>] handle_vmcall+0x1a/0x30 [kvm_intel]
>  [<ffffffffa114e592>] vmx_handle_exit+0x7a2/0x1fa0 [kvm_intel]
> ...
> 
> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
> ---

Applied, thanks.


---
Thinking whether it's time to change it to:

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 72d82ab1ee22..0c33642a4ff7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6215,15 +6215,11 @@ 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;
+	struct kvm_lapic_irq lapic_irq = {
+		.dest_id = apicid,
+		.delivery_mode = APIC_DM_REMRD,
+	};
 
-	lapic_irq.shorthand = 0;
-	lapic_irq.dest_mode = 0;
-	lapic_irq.level = 0;
-	lapic_irq.dest_id = apicid;
-	lapic_irq.msi_redir_hint = false;
-
-	lapic_irq.delivery_mode = APIC_DM_REMRD;
 	kvm_irq_delivery_to_apic(kvm, NULL, &lapic_irq, NULL);
 }