FreeBSD-SA-19:21.bhyve Security Advisory
The FreeBSD Project
Topic: Insufficient validation of guest-supplied data (e1000 device)
Credits: Reno Robert
Affects: All supported versions of FreeBSD.
Corrected: 2019-08-05 22:04:16 UTC (stable/12, 12.0-STABLE)
2019-08-06 17:13:17 UTC (releng/12.0, 12.0-RELEASE-p9)
2019-08-05 22:04:16 UTC (stable/11, 11.3-STABLE)
2019-08-06 17:13:17 UTC (releng/11.3, 11.3-RELEASE-p2)
2019-08-06 17:13:17 UTC (releng/11.2, 11.2-RELEASE-p13)
CVE Name: CVE-2019-5609
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
bhyve(8) is a hypervisor that supports running a variety of guest operating
systems in virtual machines. bhyve(8) includes an emulated Intel 82545
network interface adapter ("e1000").
II. Problem Description
The e1000 network adapters permit a variety of modifications to an Ethernet
packet when it is being transmitted. These include the insertion of IP and
TCP checksums, insertion of an Ethernet VLAN header, and TCP segmentation
offload ("TSO"). The e1000 device model uses an on-stack buffer to generate
the modified packet header when simulating these modifications on transmitted
When TCP segmentation offload is requested for a transmitted packet, the
e1000 device model used a guest-provided value to determine the size of the
on-stack buffer without validation. The subsequent header generation could
overflow an incorrectly sized buffer or indirect a pointer composed of stack
A misbehaving bhyve guest could overwrite memory in the bhyve process on the
Only the e1000 device model is affected; the virtio-net device is not
affected by this issue. If supported by the guest operating system
presenting only the virtio-net device to the guest is a suitable workaround.
No workaround is available if the e1000 device model is required.
Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date,
and restart any affected virtual machines.
1) To update your vulnerable system via a binary patch:
Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:
# freebsd-update fetch
# freebsd-update install
2) To update your vulnerable system via a source code patch:
The following patches have been verified to apply to the applicable
FreeBSD release branches.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.