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    Subject[PATCH 4.4 14/17] vfio/pci: Fix integer overflows, bitmask check
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Vlad Tsyrklevich <vlad@tsyrklevich.net>

    commit 05692d7005a364add85c6e25a6c4447ce08f913a upstream.

    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>
    Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/vfio/pci/vfio_pci.c | 35 ++++++++++++++++++++++-------------
    drivers/vfio/pci/vfio_pci_intrs.c | 2 +-
    2 files changed, 23 insertions(+), 14 deletions(-)

    --- a/drivers/vfio/pci/vfio_pci.c
    +++ b/drivers/vfio/pci/vfio_pci.c
    @@ -562,8 +562,9 @@ static long vfio_pci_ioctl(void *device_

    } 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);

    @@ -571,23 +572,31 @@ static long vfio_pci_ioctl(void *device_
    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);
    -
    - 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;
    + max = vfio_pci_get_irq_count(vdev, hdr.index);
    + if (hdr.start >= max || hdr.start + hdr.count > max)
    + 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),
    --- a/drivers/vfio/pci/vfio_pci_intrs.c
    +++ b/drivers/vfio/pci/vfio_pci_intrs.c
    @@ -255,7 +255,7 @@ static int vfio_msi_enable(struct vfio_p
    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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