Linux kernel built with the IPv6 networking support(CONFIG_IPV6) is vulnerable to setting its 'hop_limit' too low, via the neighbour discovery protocol. It could result in thwarting the IPv6 functionality. An unprivileged user on a local network could use this flaw to cause DoS to a remote system. Upstream fix: ------------- -> https://git.kernel.org/linus/6fd99094de2b83d1d4c8457f2c83483b2828e75a Reference: ---------- -> http://www.openwall.com/lists/oss-security/2015/04/04/2
Created attachment 1003851 [details] linux-3.18-ipv6-hop_limit.patch
In the attachment there is a patch for the Linux kernel that fixes this issue. Other suggested mitigations: * Disallowing Router Advertisements on a Switch level (RA filtering) * Dropping Router Advertisements that do not contain a network/route * Dropping Router Advertisements with short hop limits (hop limit < 40 or similar) Other interesting combinations is to send "route removal" packet (timeout = 0 ) in combination. Reported found that it isn't necessary, but most code paths will then delete the route if it finds it, even if it's not getting the "drop route" message from the host that advertised the route.
Statement: This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2. Future kernel updates for Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2 may address this issue. Red Hat Enterprise Linux 5 is now in Production 3 phase of the support and maintenance life cycle. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1208491]
kernel-3.19.4-100.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.
kernel-3.19.4-200.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.
kernel-4.0.0-1.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
This issue has been addressed in the following products: Red Hat Enterprise Linux 6 Via RHSA-2015:1221 https://rhn.redhat.com/errata/RHSA-2015-1221.html
This issue has been addressed in the following products: MRG for RHEL-6 v.2 Via RHSA-2015:1564 https://rhn.redhat.com/errata/RHSA-2015-1564.html
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2015:1565 https://access.redhat.com/errata/RHSA-2015:1565
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2015:1534 https://rhn.redhat.com/errata/RHSA-2015-1534.html