2021-01-12 12:29:44

by Kunkun Jiang

Subject: [PATCH] kvm: Fixes lack of KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 enabled check

The KVM_CLEAR_DIRTY_LOG ioctl lacks the check whether the capability
KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is enabled or not. This may cause
some problems if userspace calls the KVM_CLEAR_DIRTY_LOG ioctl, but
dose't enable this capability. So we'd better to add it.

Fixes: 2a31b9db15353 ("kvm: introduce manual dirty log reprotect")
Signed-off-by: Kunkun Jiang <[email protected]>
---
virt/kvm/kvm_main.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fa9e3614d30e..8f5633d8a0e8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1602,6 +1602,9 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
unsigned long *dirty_bitmap_buffer;
bool flush;

+ if (!kvm->manual_dirty_log_protect)
+ return -EPERM;
+
/* Dirty ring tracking is exclusive to dirty log tracking */
if (kvm->dirty_ring_size)
return -ENXIO;
--
2.19.1

2021-01-13 01:31:49

by Paolo Bonzini

Subject: Re: [PATCH] kvm: Fixes lack of KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 enabled check

On 12/01/21 10:29, Kunkun Jiang wrote:
> The KVM_CLEAR_DIRTY_LOG ioctl lacks the check whether the capability
> KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is enabled or not. This may cause
> some problems if userspace calls the KVM_CLEAR_DIRTY_LOG ioctl, but
> dose't enable this capability. So we'd better to add it.
>
> Fixes: 2a31b9db15353 ("kvm: introduce manual dirty log reprotect")
> Signed-off-by: Kunkun Jiang <[email protected]>
> ---
> virt/kvm/kvm_main.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index fa9e3614d30e..8f5633d8a0e8 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1602,6 +1602,9 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
> unsigned long *dirty_bitmap_buffer;
> bool flush;
>
> + if (!kvm->manual_dirty_log_protect)
> + return -EPERM;
> +
> /* Dirty ring tracking is exclusive to dirty log tracking */
> if (kvm->dirty_ring_size)
> return -ENXIO;

This is not a problem, KVM_CLEAR_DIRTY_LOG can always be used even if
KVM_CAP_MANUAL_DIRTY_LOG_PROTECT was not enabled. The meaning is the
same: clear the bits without returning them.

Paolo