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: <Stable@xxxxxxxxxxxxxxx> # v4.18+
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Reported-by: Gavin Shan <gshan@xxxxxxxxxx>
> ---
> 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
>
