2021-04-13 03:19:46

by Eric Auger

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

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: <[email protected]> # v4.18+
Signed-off-by: Eric Auger <[email protected]>
Reported-by: Gavin Shan <[email protected]>
---
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(&vgic->rd_regions,
- struct vgic_redist_region, list);
+ rdreg = list_first_entry_or_null(&vgic->rd_regions,
+ struct vgic_redist_region, list);
if (!rdreg)
addr_ptr = &undef_value;
else
--
2.26.3

2021-04-13 08:58:25

by Keqian Zhu

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

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: <[email protected]> # v4.18+
> Signed-off-by: Eric Auger <[email protected]>
> Reported-by: Gavin Shan <[email protected]>
> ---
> 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(&vgic->rd_regions,
> - struct vgic_redist_region, list);
> + rdreg = list_first_entry_or_null(&vgic->rd_regions,
> + struct vgic_redist_region, list);
> if (!rdreg)
> addr_ptr = &undef_value;
> else
>

2021-04-13 19:34:08

by Marc Zyngier

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

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.