CVE-2022-48910

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: ipv6: ensure we call ipv6_mc_down() at most once

There are two reasons for addrconf_notify() to be called with NETDEV_DOWN:

either the network device is actually going down, or IPv6 was disabled

on the interface.

If either of them stays down while the other is toggled, we repeatedly

call the code for NETDEV_DOWN, including ipv6_mc_down(), while never

calling the corresponding ipv6_mc_up() in between. This will cause a

new entry in idev->mc_tomb to be allocated for each multicast group

the interface is subscribed to, which in turn leaks one struct ifmcaddr6

per nontrivial multicast group the interface is subscribed to.

The following reproducer will leak at least $n objects:

ip addr add ff2e::4242/32 dev eth0 autojoin

sysctl -w net.ipv6.conf.eth0.disable_ipv6=1

for i in $(seq 1 $n); do

ip link set up eth0; ip link set down eth0

done

Joining groups with IPV6_ADD_MEMBERSHIP (unprivileged) or setting the

sysctl

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References