[PATCH 5.11 108/601] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

Greg Kroah-Hartman
2021-05-12T17:05:05Z

From: Eric Auger <eric.auger@redhat.com>

commit 94ac0835391efc1a30feda6fc908913ec012951e upstream.

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: <Stable@vger.kernel.org> # v4.18+
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reported-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210412150034.29185-1-eric.auger@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kvm/vgic/vgic-kvm-device.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- 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, unsig
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