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 --- arch/arm64/kvm/vgic/vgic-its.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 2dad2d095160..e2764d0ffa9f 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -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; }

base-commit: 33cc938e65a98f1d29d0a18403dbbee050dcad9a