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vfio/pci: Fix integer overflows, bitmask check

The VFIO_DEVICE_SET_IRQS ioctl did not sufficiently sanitize
user-supplied integers, potentially allowing memory corruption. This
patch adds appropriate integer overflow checks, checks the range bounds
for VFIO_IRQ_SET_DATA_NONE, and also verifies that only single element
in the VFIO_IRQ_SET_DATA_TYPE_MASK bitmask is set.
VFIO_IRQ_SET_ACTION_TYPE_MASK is already correctly checked later in
vfio_pci_set_irqs_ioctl().

Furthermore, a kzalloc is changed to a kcalloc because the use of a
kzalloc with an integer multiplication allowed an integer overflow
condition to be reached without this patch. kcalloc checks for overflow
and should prevent a similar occurrence.

Signed-off-by: Vlad Tsyrklevich <vlad@tsyrklevich.net>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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vlad902 authored and awilliam committed Oct 12, 2016
1 parent 07d9a38 commit 05692d7005a364add85c6e25a6c4447ce08f913a
Showing with 22 additions and 13 deletions.
  1. +21 −12 drivers/vfio/pci/vfio_pci.c
  2. +1 −1 drivers/vfio/pci/vfio_pci_intrs.c
@@ -829,32 +829,41 @@ static long vfio_pci_ioctl(void *device_data,

} else if (cmd == VFIO_DEVICE_SET_IRQS) {
struct vfio_irq_set hdr;
size_t size;
u8 *data = NULL;
int ret = 0;
int max, ret = 0;

minsz = offsetofend(struct vfio_irq_set, count);

if (copy_from_user(&hdr, (void __user *)arg, minsz))
return -EFAULT;

if (hdr.argsz < minsz || hdr.index >= VFIO_PCI_NUM_IRQS ||
hdr.count >= (U32_MAX - hdr.start) ||
hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
VFIO_IRQ_SET_ACTION_TYPE_MASK))
return -EINVAL;

if (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE)) {
size_t size;
int max = vfio_pci_get_irq_count(vdev, hdr.index);
max = vfio_pci_get_irq_count(vdev, hdr.index);
if (hdr.start >= max || hdr.start + hdr.count > max)
return -EINVAL;

if (hdr.flags & VFIO_IRQ_SET_DATA_BOOL)
size = sizeof(uint8_t);
else if (hdr.flags & VFIO_IRQ_SET_DATA_EVENTFD)
size = sizeof(int32_t);
else
return -EINVAL;
switch (hdr.flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
case VFIO_IRQ_SET_DATA_NONE:
size = 0;
break;
case VFIO_IRQ_SET_DATA_BOOL:
size = sizeof(uint8_t);
break;
case VFIO_IRQ_SET_DATA_EVENTFD:
size = sizeof(int32_t);
break;
default:
return -EINVAL;
}

if (hdr.argsz - minsz < hdr.count * size ||
hdr.start >= max || hdr.start + hdr.count > max)
if (size) {
if (hdr.argsz - minsz < hdr.count * size)
return -EINVAL;

data = memdup_user((void __user *)(arg + minsz),
@@ -256,7 +256,7 @@ static int vfio_msi_enable(struct vfio_pci_device *vdev, int nvec, bool msix)
if (!is_irq_none(vdev))
return -EINVAL;

vdev->ctx = kzalloc(nvec * sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
vdev->ctx = kcalloc(nvec, sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
if (!vdev->ctx)
return -ENOMEM;

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