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From patchwork Wed Oct 12 16:51:24 2016
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: [v3] vfio/pci: Fix integer overflows, bitmask check
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From: Vlad Tsyrklevich <vlad@tsyrklevich.net>
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X-Patchwork-Id: 9373631
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Message-Id: <1476291084-50737-1-git-send-email-vlad@tsyrklevich.net>
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To: kvm@vger.kernel.org
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Cc: alex.williamson@redhat.com, Vlad Tsyrklevich <vlad@tsyrklevich.net>
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Date: Wed, 12 Oct 2016 18:51:24 +0200
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The VFIO_DEVICE_SET_IRQS ioctl did not sufficiently sanitize
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user-supplied integers, potentially allowing memory corruption. This
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patch adds appropriate integer overflow checks, checks the range bounds
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for VFIO_IRQ_SET_DATA_NONE, and also verifies that only single element
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in the VFIO_IRQ_SET_DATA_TYPE_MASK bitmask is set.
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VFIO_IRQ_SET_ACTION_TYPE_MASK is already correctly checked later in
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vfio_pci_set_irqs_ioctl().
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Furthermore, a kzalloc is changed to a kcalloc because the use of a
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kzalloc with an integer multiplication allowed an integer overflow
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condition to be reached without this patch. kcalloc checks for overflow
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and should prevent a similar occurrence.
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Signed-off-by: Vlad Tsyrklevich <vlad@tsyrklevich.net>
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---
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drivers/vfio/pci/vfio_pci.c | 33 +++++++++++++++++++++------------
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drivers/vfio/pci/vfio_pci_intrs.c | 2 +-
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2 files changed, 22 insertions(+), 13 deletions(-)
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diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
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index d624a52..031bc08 100644
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--- a/drivers/vfio/pci/vfio_pci.c
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+++ b/drivers/vfio/pci/vfio_pci.c
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@@ -829,8 +829,9 @@ static long vfio_pci_ioctl(void *device_data,
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} else if (cmd == VFIO_DEVICE_SET_IRQS) {
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struct vfio_irq_set hdr;
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+ size_t size;
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u8 *data = NULL;
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- int ret = 0;
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+ int max, ret = 0;
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minsz = offsetofend(struct vfio_irq_set, count);
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@@ -838,23 +839,31 @@ static long vfio_pci_ioctl(void *device_data,
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return -EFAULT;
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if (hdr.argsz < minsz || hdr.index >= VFIO_PCI_NUM_IRQS ||
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+ hdr.count >= (U32_MAX - hdr.start) ||
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hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
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VFIO_IRQ_SET_ACTION_TYPE_MASK))
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return -EINVAL;
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- if (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE)) {
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- size_t size;
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- int max = vfio_pci_get_irq_count(vdev, hdr.index);
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+ max = vfio_pci_get_irq_count(vdev, hdr.index);
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+ if (hdr.start >= max || hdr.start + hdr.count > max)
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+ return -EINVAL;
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- if (hdr.flags & VFIO_IRQ_SET_DATA_BOOL)
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- size = sizeof(uint8_t);
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- else if (hdr.flags & VFIO_IRQ_SET_DATA_EVENTFD)
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- size = sizeof(int32_t);
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- else
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- return -EINVAL;
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+ switch (hdr.flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
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+ case VFIO_IRQ_SET_DATA_NONE:
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+ size = 0;
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+ break;
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+ case VFIO_IRQ_SET_DATA_BOOL:
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+ size = sizeof(uint8_t);
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+ break;
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+ case VFIO_IRQ_SET_DATA_EVENTFD:
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+ size = sizeof(int32_t);
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+ break;
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+ default:
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+ return -EINVAL;
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+ }
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- if (hdr.argsz - minsz < hdr.count * size ||
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- hdr.start >= max || hdr.start + hdr.count > max)
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+ if (size) {
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+ if (hdr.argsz - minsz < hdr.count * size)
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return -EINVAL;
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data = memdup_user((void __user *)(arg + minsz),
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diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
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index c2e6089..1c46045 100644
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--- a/drivers/vfio/pci/vfio_pci_intrs.c
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+++ b/drivers/vfio/pci/vfio_pci_intrs.c
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@@ -256,7 +256,7 @@ static int vfio_msi_enable(struct vfio_pci_device *vdev, int nvec, bool msix)
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if (!is_irq_none(vdev))
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return -EINVAL;
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- vdev->ctx = kzalloc(nvec * sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
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+ vdev->ctx = kcalloc(nvec, sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL);
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if (!vdev->ctx)
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return -ENOMEM;
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