5.4-stable review patch. If anyone has any objections, please let me know.
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From: Oliver Upton oliver.upton@linux.dev
[ Upstream commit ad362fe07fecf0aba839ff2cc59a3617bd42c33f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- virt/kvm/arm/vgic/vgic-its.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index e06bb8ed7688..0533881bd2ab 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -581,7 +581,11 @@ 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; @@ -761,6 +765,7 @@ 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; }