2019-11-28 06:40:25

by Miaohe Lin

Subject: [PATCH] KVM: vgic: Fix potential double free dist->spis in __kvm_vgic_destroy()

From: Miaohe Lin <[email protected]>

In kvm_vgic_dist_init() called from kvm_vgic_map_resources(), if
dist->vgic_model is invalid, dist->spis will be freed without set
dist->spis = NULL. And in vgicv2 resources clean up path,
__kvm_vgic_destroy() will be called to free allocated resources.
And dist->spis will be freed again in clean up chain because we
forget to set dist->spis = NULL in kvm_vgic_dist_init() failed
path. So double free would happen.

Signed-off-by: Miaohe Lin <[email protected]>
---
virt/kvm/arm/vgic/vgic-init.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 53e3969dfb52..c17c29beeb72 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -171,6 +171,7 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
break;
default:
kfree(dist->spis);
+ dist->spis = NULL;
return -EINVAL;
}
}
--
2.19.1

2019-11-28 09:00:52

by Eric Auger

Subject: Re: [PATCH] KVM: vgic: Fix potential double free dist->spis in __kvm_vgic_destroy()

Hi,

On 11/28/19 7:38 AM, linmiaohe wrote:
> From: Miaohe Lin <[email protected]>
>
> In kvm_vgic_dist_init() called from kvm_vgic_map_resources(), if
> dist->vgic_model is invalid, dist->spis will be freed without set
> dist->spis = NULL. And in vgicv2 resources clean up path,
> __kvm_vgic_destroy() will be called to free allocated resources.
> And dist->spis will be freed again in clean up chain because we
> forget to set dist->spis = NULL in kvm_vgic_dist_init() failed
> path. So double free would happen.
>
> Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Eric Auger <[email protected]>

Thanks

Eric

> ---
> virt/kvm/arm/vgic/vgic-init.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 53e3969dfb52..c17c29beeb72 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -171,6 +171,7 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
> break;
> default:
> kfree(dist->spis);
> + dist->spis = NULL;
> return -EINVAL;
> }
> }
>

2019-12-06 11:54:31

by Marc Zyngier

Subject: Re: [PATCH] KVM: vgic: Fix potential double free dist->spis in __kvm_vgic_destroy()

On 2019-11-28 06:38, linmiaohe wrote:
> From: Miaohe Lin <[email protected]>
>
> In kvm_vgic_dist_init() called from kvm_vgic_map_resources(), if
> dist->vgic_model is invalid, dist->spis will be freed without set
> dist->spis = NULL. And in vgicv2 resources clean up path,
> __kvm_vgic_destroy() will be called to free allocated resources.
> And dist->spis will be freed again in clean up chain because we
> forget to set dist->spis = NULL in kvm_vgic_dist_init() failed
> path. So double free would happen.
>
> Signed-off-by: Miaohe Lin <[email protected]>
> ---
> virt/kvm/arm/vgic/vgic-init.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-init.c
> b/virt/kvm/arm/vgic/vgic-init.c
> index 53e3969dfb52..c17c29beeb72 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -171,6 +171,7 @@ static int kvm_vgic_dist_init(struct kvm *kvm,
> unsigned int nr_spis)
> break;
> default:
> kfree(dist->spis);
> + dist->spis = NULL;
> return -EINVAL;
> }
> }

Applied, thanks.

M.
--
Jazz is not dead. It just smells funny...