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Commit 99e5e886 authored by Christoffer Dall's avatar Christoffer Dall
Browse files

KVM: arm64: vgic-its: Handle errors from vgic_add_lpi 



During low memory conditions, we could be dereferencing a NULL pointer
when vgic_add_lpi fails to allocate memory.

Consider for example this call sequence:

  vgic_its_cmd_handle_mapi
      itte->irq = vgic_add_lpi(kvm, lpi_nr);
          update_lpi_config(kvm, itte->irq, NULL);
              ret = kvm_read_guest(kvm, propbase + irq->intid
	                                             ^^^^
						     kaboom?

Instead, return an error pointer from vgic_add_lpi and check the return
value from its single caller.

Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent fd837b08

virt/kvm/arm/vgic/vgic-its.c

+17 −4
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid) 


	irq = kzalloc(sizeof(struct vgic_irq), GFP_KERNEL);

	if (!irq)

		return NULL;

		return ERR_PTR(-ENOMEM);



	INIT_LIST_HEAD(&irq->lpi_list);

	INIT_LIST_HEAD(&irq->ap_list);
@@ -522,6 +522,7 @@ static void its_free_itte(struct kvm *kvm, struct its_itte *itte) 
	list_del(&itte->itte_list);



	/* This put matches the get in vgic_add_lpi. */

	if (itte->irq)

		vgic_put_irq(kvm, itte->irq);



	kfree(itte);
@@ -713,10 +714,11 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its, 
	u32 device_id = its_cmd_get_deviceid(its_cmd);

	u32 event_id = its_cmd_get_id(its_cmd);

	u32 coll_id = its_cmd_get_collection(its_cmd);

	struct its_itte *itte;

	struct its_itte *itte, *new_itte = NULL;

	struct its_device *device;

	struct its_collection *collection, *new_coll = NULL;

	int lpi_nr;

	struct vgic_irq *irq;



	device = find_its_device(its, device_id);

	if (!device)
@@ -747,13 +749,24 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its, 
			return -ENOMEM;

		}



		new_itte = itte;

		itte->event_id	= event_id;

		list_add_tail(&itte->itte_list, &device->itt_head);

	}



	itte->collection = collection;

	itte->lpi = lpi_nr;

	itte->irq = vgic_add_lpi(kvm, lpi_nr);



	irq = vgic_add_lpi(kvm, lpi_nr);

	if (IS_ERR(irq)) {

		if (new_coll)

			vgic_its_free_collection(its, coll_id);

		if (new_itte)

			its_free_itte(kvm, new_itte);

		return PTR_ERR(irq);

	}

	itte->irq = irq;



	update_affinity_itte(kvm, itte);



	/*