linux-kernel - [PATCH 4.19 077/109] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE

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Message-Id: <20210628143305.32978-78-sashal@kernel.org>
Date:   Mon, 28 Jun 2021 10:32:33 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Eric Auger <eric.auger@...hat.com>, Stable@...r.kernel.org,
        Gavin Shan <gshan@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 4.19 077/109] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

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

diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
index 6ada2432e37c..71d92096776e 100644
--- a/virt/kvm/arm/vgic/vgic-kvm-device.c
+++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
@@ -95,8 +95,8 @@ 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
-- 
2.30.2