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

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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: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Christoffer Dall 2016-08-01 20:25:33 +02:00
parent fd837b08d9
commit 99e5e886a0
1 changed files with 17 additions and 4 deletions
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21
virt/kvm/arm/vgic/vgic-its.c
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@ -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);
@ -522,7 +522,8 @@ 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. */
vgic_put_irq(kvm, itte->irq);
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);
/*