[PATCH 6.8 093/336] KVM: arm64: vgic-v2: Check for non-NULL vCPU in vgic_v2_parse_attr()

Greg Kroah-Hartman
2024-05-14T10:30:53Z

From: Oliver Upton <oliver.upton@linux.dev>

[ Upstream commit 6ddb4f372fc63210034b903d96ebbeb3c7195adb ]

vgic_v2_parse_attr() is responsible for finding the vCPU that matches
the user-provided CPUID, which (of course) may not be valid. If the ID
is invalid, kvm_get_vcpu_by_id() returns NULL, which isn't handled
gracefully.

Similar to the GICv3 uaccess flow, check that kvm_get_vcpu_by_id()
actually returns something and fail the ioctl if not.

Cc: stable@vger.kernel.org
Fixes: 7d450e282171 ("KVM: arm/arm64: vgic-new: Add userland access to VGIC dist registers")
Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240424173959.3776798-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kvm/vgic/vgic-kvm-device.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c
index f48b8dab8b3d2..1d26bb5b02f4b 100644
--- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
+++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
@@ -338,12 +338,12 @@ int kvm_register_vgic_device(unsigned long type)
int vgic_v2_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr,
struct vgic_reg_attr *reg_attr)
{
- int cpuid;
+ int cpuid = FIELD_GET(KVM_DEV_ARM_VGIC_CPUID_MASK, attr->attr);

- cpuid = FIELD_GET(KVM_DEV_ARM_VGIC_CPUID_MASK, attr->attr);
-
- reg_attr->vcpu = kvm_get_vcpu_by_id(dev->kvm, cpuid);
reg_attr->addr = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
+ reg_attr->vcpu = kvm_get_vcpu_by_id(dev->kvm, cpuid);
+ if (!reg_attr->vcpu)
+ return -EINVAL;

return 0;
}
--
2.43.0