Re: [PATCH] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

[Marc Zyngier]

On Mon, 12 Apr 2021 17:00:34 +0200, Eric Auger wrote:
> When reading the base address of the a REDIST region
> through KVM_VGIC_V3_ADDR_TYPE_REDIST we expect the
> redistributor region list to be populated with a single
> element.
> 
> However list_first_entry() expects the list to be non empty.
> Instead we should use list_first_entry_or_null which effectively
> returns NULL if the list is empty.

Applied to kvm-arm64/vgic-5.13, thanks!

[1/1] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read
  commit: 94ac0835391efc1a30feda6fc908913ec012951e

Cheers,

M.
-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

[Keqian Zhu]

On 2021/4/12 23:00, Eric Auger wrote:
> When reading the base address of the a REDIST region
> through KVM_VGIC_V3_ADDR_TYPE_REDIST we expect the
> redistributor region list to be populated with a single
> element.
> 
> However list_first_entry() expects the list to be non empty.
Indeed, list_first_entry() always return a non-null ptr. If the list
is empty, it will mistake the list head as the first element.

> Instead we should use list_first_entry_or_null which effectively
> returns NULL if the list is empty.
> 
> Fixes: dbd9733ab674 ("KVM: arm/arm64: Replace the single rdist region by a 
> list")
> Cc:  # v4.18+
> Signed-off-by: Eric Auger 
> Reported-by: Gavin Shan 
> ---
>  arch/arm64/kvm/vgic/vgic-kvm-device.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c 
> b/arch/arm64/kvm/vgic/vgic-kvm-device.c
> index 44419679f91a..5eaede3e3b5a 100644
> --- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
> +++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
> @@ -87,8 +87,8 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 
> *addr, bool write)
>   r = vgic_v3_set_redist_base(kvm, 0, *addr, 0);
>   goto out;
>   }
> - rdreg = list_first_entry(>rd_regions,
> -  struct vgic_redist_region, list);
> + rdreg = list_first_entry_or_null(>rd_regions,
> +  struct vgic_redist_region, 
> list);
>   if (!rdreg)
>   addr_ptr = _value;
>   else
> 

[PATCH] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

[Eric Auger]

When reading the base address of the a REDIST region
through KVM_VGIC_V3_ADDR_TYPE_REDIST we expect the
redistributor region list to be populated with a single
element.

However list_first_entry() expects the list to be non empty.
Instead we should use list_first_entry_or_null which effectively
returns NULL if the list is empty.

Fixes: dbd9733ab674 ("KVM: arm/arm64: Replace the single rdist region by a 
list")
Cc:  # v4.18+
Signed-off-by: Eric Auger 
Reported-by: Gavin Shan 
---
 arch/arm64/kvm/vgic/vgic-kvm-device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c 
b/arch/arm64/kvm/vgic/vgic-kvm-device.c
index 44419679f91a..5eaede3e3b5a 100644
--- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
+++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
@@ -87,8 +87,8 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 
*addr, bool write)
r = vgic_v3_set_redist_base(kvm, 0, *addr, 0);
goto out;
}
-   rdreg = list_first_entry(>rd_regions,
-struct vgic_redist_region, list);
+   rdreg = list_first_entry_or_null(>rd_regions,
+struct vgic_redist_region, 
list);
if (!rdreg)
addr_ptr = _value;
else
-- 
2.26.3