FreeBSD-SA-20:20.ipv6 Security Advisory
The FreeBSD Project
Topic: IPv6 socket option race condition and use after free
Credits: syzkaller, Andy Nguyen
Affects: All supported versions of FreeBSD.
Corrected: 2020-04-02 15:30:51 UTC (stable/12, 12.1-STABLE)
2020-07-08 20:11:40 UTC (releng/12.1, 12.1-RELEASE-p7)
2020-07-06 20:23:14 UTC (stable/11, 11.4-STABLE)
2020-07-08 20:11:40 UTC (releng/11.4, 11.4-RELEASE-p1)
2020-07-08 20:11:40 UTC (releng/11.3, 11.3-RELEASE-p11)
CVE Name: CVE-2020-7457
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/>.
The IPV6_2292PKTOPTIONS socket option allows user code to set IPv6
header options on a socket.
II. Problem Description
The IPV6_2292PKTOPTIONS set handler was missing synchronization,
so racing accesses could modify freed memory.
A malicious user application could trigger memory corruption, leading
to privilege escalation.
No workaround is available.
Upgrade your vulnerable system to a supported FreeBSD stable or release /
security branch (releng) dated after the correction date and reboot.
Perform one of the following:
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
# shutdown -r +10min "Rebooting for a security update"
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.