2017-08-02 03:23:10

by Longpeng(Mike)

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

'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) <[email protected]>
---
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

2017-08-02 08:14:31

by Paolo Bonzini

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

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) <[email protected]>
> ---
> 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

2017-08-02 20:30:59

by Radim Krčmář

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

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) <[email protected]>
> ---

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);
}