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From patchwork Wed Oct 12 16:51:24 2016
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: [v3] vfio/pci: Fix integer overflows, bitmask check
From: Vlad Tsyrklevich <vlad@tsyrklevich.net>
X-Patchwork-Id: 9373631
Message-Id: <1476291084-50737-1-git-send-email-vlad@tsyrklevich.net>
To: kvm@vger.kernel.org
Cc: alex.williamson@redhat.com, Vlad Tsyrklevich <vlad@tsyrklevich.net>
Date: Wed, 12 Oct 2016 18:51:24 +0200
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>
---
drivers/vfio/pci/vfio_pci.c | 33 +++++++++++++++++++++------------
drivers/vfio/pci/vfio_pci_intrs.c | 2 +-
2 files changed, 22 insertions(+), 13 deletions(-)
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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