From: Oliver Upton <oliver.upton@linux.dev>
To: kvmarm@lists.linux.dev
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
kvm@vger.kernel.org, Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Oliver Upton <oliver.upton@linux.dev>,
stable@vger.kernel.org
Subject: [PATCH 1/2] KVM: arm64: vgic-v2: Check for non-NULL vCPU in vgic_v2_parse_attr()
Date: Wed, 24 Apr 2024 17:39:58 +0000 [thread overview]
Message-ID: <20240424173959.3776798-2-oliver.upton@linux.dev> (raw)
In-Reply-To: <20240424173959.3776798-1-oliver.upton@linux.dev>
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>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
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 f48b8dab8b3d..1d26bb5b02f4 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;
}
--
2.44.0.769.g3c40516874-goog
next prev parent reply other threads:[~2024-04-24 17:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-24 17:39 [PATCH 0/2] KVM: arm64: Avoid NULL dereference in vgic-v2 device attr accessors Oliver Upton
2024-04-24 17:39 ` Oliver Upton [this message]
2024-04-24 17:39 ` [PATCH 2/2] KVM: selftests: Add test for uaccesses to non-existent vgic-v2 CPUIF Oliver Upton
2024-04-24 18:06 ` [PATCH 0/2] KVM: arm64: Avoid NULL dereference in vgic-v2 device attr accessors Marc Zyngier
2024-04-24 19:15 ` Oliver Upton
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