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KVM: arm64: vgic-its: Avoid potential UAF in LPI translation cache

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There is a potential UAF scenario in the case of an LPI translation
cache hit racing with an operation that invalidates the cache, such
as a DISCARD ITS command. The root of the problem is that
vgic_its_check_cache() does not elevate the refcount on the vgic_irq
before dropping the lock that serializes refcount changes.

Have vgic_its_check_cache() raise the refcount on the returned vgic_irq
and add the corresponding decrement after queueing the interrupt.

Cc: stable@vger.kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240104183233.3560639-1-oliver.upton@linux.dev
This commit is contained in:
Oliver Upton 2024-01-04 18:32:32 +00:00 committed by Marc Zyngier
parent 39084ba8d0
commit ad362fe07f
1 changed files with 5 additions and 0 deletions
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5
arch/arm64/kvm/vgic/vgic-its.c
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@ -590,7 +590,11 @@ static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
unsigned long flags;
raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
irq = __vgic_its_check_cache(dist, db, devid, eventid);
if (irq)
vgic_get_irq_kref(irq);
raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
return irq;
@ -769,6 +773,7 @@ int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
raw_spin_lock_irqsave(&irq->irq_lock, flags);
irq->pending_latch = true;
vgic_queue_irq_unlock(kvm, irq, flags);
vgic_put_irq(kvm, irq);
return 0;
}