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>

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index d624a52..031bc08 100644 (file)
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -829,8 +829,9 @@ 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);
 
@@ -838,23 +839,31 @@ static long vfio_pci_ioctl(void *device_data,
                        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),

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index c2e6089..1c46045 100644 (file)
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -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;