Re: [PATCH v3 01/12] KVM: arm/arm64: Set dist->spis to NULL after kfree

[Christoffer Dall]

On Fri, Apr 13, 2018 at 10:20:47AM +0200, Eric Auger wrote:
> in case kvm_vgic_map_resources() fails, typically if the vgic
> distributor is not defined, __kvm_vgic_destroy will be called
> several times. Indeed kvm_vgic_map_resources() is called on
> first vcpu run. As a result dist->spis is freeed more than once
> and on the second time it causes a "kernel BUG at mm/slub.c:3912!"
> 
> Set dist->spis to NULL to avoid the crash.
> 
> Fixes: ad275b8bb1e6 ("KVM: arm/arm64: vgic-new: vgic_init: implement
> vgic_init")
> 
> Signed-off-by: Eric Auger 
> Reviewed-by: Marc Zyngier 

Reviewed-by: Christoffer Dall 

> 
> ---
> 
> v2 -> v3:
> - added Marc's R-b and Fixed commit
> ---
>  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 68378fe..c52f03d 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -308,6 +308,7 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
>   dist->initialized = false;
>  
>   kfree(dist->spis);
> + dist->spis = NULL;
>   dist->nr_spis = 0;
>  
>   if (vgic_supports_direct_msis(kvm))
> -- 
> 2.5.5
> 

[PATCH v3 01/12] KVM: arm/arm64: Set dist->spis to NULL after kfree

[Eric Auger]

in case kvm_vgic_map_resources() fails, typically if the vgic
distributor is not defined, __kvm_vgic_destroy will be called
several times. Indeed kvm_vgic_map_resources() is called on
first vcpu run. As a result dist->spis is freeed more than once
and on the second time it causes a "kernel BUG at mm/slub.c:3912!"

Set dist->spis to NULL to avoid the crash.

Fixes: ad275b8bb1e6 ("KVM: arm/arm64: vgic-new: vgic_init: implement
vgic_init")

Signed-off-by: Eric Auger 
Reviewed-by: Marc Zyngier 

---

v2 -> v3:
- added Marc's R-b and Fixed commit
---
 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 68378fe..c52f03d 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -308,6 +308,7 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
dist->initialized = false;
 
kfree(dist->spis);
+   dist->spis = NULL;
dist->nr_spis = 0;
 
if (vgic_supports_direct_msis(kvm))
-- 
2.5.5