On Wed, 12 Oct 2016 18:51:24 +0200
Vlad Tsyrklevich <vlad@xxxxxxxxxxxxxxx> wrote:
> 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@xxxxxxxxxxxxxxx>
> ---
> drivers/vfio/pci/vfio_pci.c | 33 +++++++++++++++++++++------------
> drivers/vfio/pci/vfio_pci_intrs.c | 2 +-
> 2 files changed, 22 insertions(+), 13 deletions(-)
I've applied this to my for-linus branch for v4.9, thanks,
Alex
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index d624a52..031bc08 100644
> --- 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
> --- 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;
>
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