| Message ID | 20130326131358.GA11516@longonot.mountain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Mar 26, 2013 at 04:13:58PM +0300, Dan Carpenter wrote: > The worry here is that a large value of hdr.start would cause a > read before the start of the array and a crash in > vfio_msi_set_vector_signal(). > > The check in vfio_msi_set_block() is not enough: > > if (start + count > vdev->num_ctx) > return -EINVAL; > > A large value of "start" would lead to an integer overflow. > > The check in vfio_msi_set_vector_signal() doesn't work either: > > if (vector >= vdev->num_ctx) > return -EINVAL; > > Here "vector" is "count" casted to a signed int so it would be negative ^^^^^ I meant "start" not "count". > and thus smaller than "vdev->num_ctx" which is also a signed int. > Gar... I hate this patch already. I really should make vdev->num_ctx an unsigned int. I'll send that in a v2 along with whatever other suggestions people send. regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index acfcb1a..de54f69 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -371,6 +371,9 @@ static long vfio_pci_ioctl(void *device_data, hdr.count > vfio_pci_get_irq_count(vdev, hdr.index)) return -EINVAL; + if (hdr.start > INT_MAX - hdr.count) + return -EINVAL; + data = memdup_user((void __user *)(arg + minsz), hdr.count * size); if (IS_ERR(data))
The worry here is that a large value of hdr.start would cause a read before the start of the array and a crash in vfio_msi_set_vector_signal(). The check in vfio_msi_set_block() is not enough: if (start + count > vdev->num_ctx) return -EINVAL; A large value of "start" would lead to an integer overflow. The check in vfio_msi_set_vector_signal() doesn't work either: if (vector >= vdev->num_ctx) return -EINVAL; Here "vector" is "count" casted to a signed int so it would be negative and thus smaller than "vdev->num_ctx" which is also a signed int. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- Static analysis stuff. Untested. This patch is not beautiful. There is probably a better limit to use if I knew the code. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html