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Re: [PATCH 1/1] kvm: Clear variables which may not be used
From: |
Daniel P . Berrangé |
Subject: |
Re: [PATCH 1/1] kvm: Clear variables which may not be used |
Date: |
Mon, 6 Dec 2021 11:39:34 +0000 |
User-agent: |
Mutt/2.1.3 (2021-09-10) |
On Mon, Dec 06, 2021 at 12:27:38PM +0100, Li Zhang wrote:
> The variables msi, route in kvm_irqchip_send_msi may be uninitialised
> values in some cases. It's necessary to clear them.
You say the patch is going to 'clear them' but....
>
> Signed-off-by: Li Zhang <lizhang@suse.de>
> ---
> accel/kvm/kvm-all.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index eecd8031cf..bd50dc6b80 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -1913,10 +1913,8 @@ static KVMMSIRoute *kvm_lookup_msi_route(KVMState *s,
> MSIMessage msg)
>
> int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg)
> {
> - struct kvm_msi msi;
> - KVMMSIRoute *route;
> -
> if (kvm_direct_msi_allowed) {
> + struct kvm_msi msi;
...but this is still an uninitialized declaration.
> msi.address_lo = (uint32_t)msg.address;
> msi.address_hi = msg.address >> 32;
> msi.data = le32_to_cpu(msg.data);
I guess the bug you were wanting to fix is that this code only
initializes 5 out of 6 struct fields, before calling the
ioctl.
> @@ -1926,6 +1924,7 @@ int kvm_irqchip_send_msi(KVMState *s, MSIMessage msg)
> return kvm_vm_ioctl(s, KVM_SIGNAL_MSI, &msi);
> }
>
> + KVMMSIRoute *route;
This was initialized correctly before and didn't need moving
> route = kvm_lookup_msi_route(s, msg);
> if (!route) {
> int virq;
Regards,
Daniel
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