Headline
CVE-2019-5609
In FreeBSD 12.0-STABLE before r350619, 12.0-RELEASE before 12.0-RELEASE-p9, 11.3-STABLE before r350619, 11.3-RELEASE before 11.3-RELEASE-p2, and 11.2-RELEASE before 11.2-RELEASE-p13, the bhyve e1000 device emulation used a guest-provided value to determine the size of the on-stack buffer without validation when TCP segmentation offload is requested for a transmitted packet. A misbehaving bhyve guest could overwrite memory in the bhyve process on the host.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-19:21.bhyve Security Advisory The FreeBSD Project Topic: Insufficient validation of guest-supplied data (e1000 device) Category: core Module: bhyve Announced: 2019-08-06 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 . I. Background 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 packets. 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 garbage. III. Impact A misbehaving bhyve guest could overwrite memory in the bhyve process on the host. IV. Workaround 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. V. Solution 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. # fetch https://security.FreeBSD.org/patches/SA-19:21/bhyve.patch # fetch https://security.FreeBSD.org/patches/SA-19:21/bhyve.patch.asc # gpg --verify bhyve.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating system using buildworld and installworld as described in . Restart the applicable virtual machines, or reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/12/ r350619 releng/12.0/ r350647 stable/11/ r350619 releng/11.3/ r350647 releng/11.2/ r350647 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl1Jt1xfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cL0qA//ZdapXUMl6KuuvtZIveMZgNdMVLYaqB1K8yHXO5udd58fTsH6+Khei0LT gYGxDEJkHinM1EWy688xE+PSzb9twmEmawW4N4WMhWB9oMoTuLQ5E4Zm9my1TdDh ducK6Q4GqOojIXJ0LtHDqs9qveAfkgB6L6jmLt/1jpZelLupte3S+bPmI4yta7ge 7k54V9GcN05i7wX2TaZA7H3ROQziW537ZeoRB8BQwt7bekFw2uBfO9s0CWcJZPnG +0D6QEsRqbtYMJr5RkUCc1y4qaqnWBBn/Zyyr0P+bXZklU/IW2GJTDWNObXN7DPE NOhuVY7PQHN6jv3u+nKa1AY7mjI3zBo009iAfPQFCb9Kn08tJ2A9WrExEMwZdcbI nXVqCRdp7xCSPO73vjNv4btzvAU7iwbaBkpGFs721cH72ImvmXi7TwepPEAul0do VwKYMxhStZtoDQhEea1eq41KNvqxmA/mkbEjpKcTZCUJq7xVyV4uaVme3Uq45uaa mKMWx+Gg09A2Y5NfSCiz9AGuMkIGn05hKIOK39yAG159uTks60Ybsw/bOnE9WnMJ 5igcI+U6utIMi2M6nH4rn/wKBYM9cHWmQLfo6kECUi2CCTmR5VL8BTJ/8vHCqXi1 vCcAPacKYAROsvGQyynSVLiXJAXOrc8/VyoXRHC5cAapVeParcw= =0XzG -----END PGP SIGNATURE-----
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This vulnerability allows local attackers to escalate privileges on affected installations of xhyve. An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the e1000 virtual device. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a stack-based buffer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the hypervisor. Was ZDI-CAN-15056.