FreeBSD: VID-8EED0C5C-3482-11EB-B87A-901B0EF719AB (CVE-2020-7469): FreeBSD -- ICMPv6 use-after-free in error message handling

Description

Details for this vulnerability have not been published by NIST at this point. Descriptions from software vendor advisories for this issue are provided below.

From VID-8EED0C5C-3482-11EB-B87A-901B0EF719AB:

Problem Description:

When an ICMPv6 error message is received, the FreeBSD ICMPv6 stack

may extract information from the message to hand to upper-layer

protocols. As a part of this operation, it may parse IPv6 header

options from a packet embedded in the ICMPv6 message.

The handler for a routing option caches a pointer into the packet

buffer holding the ICMPv6 message. However, when processing

subsequent options the packet buffer may be freed, rendering the

cached pointer invalid. The network stack may later dereference the

pointer, potentially triggering a use-after-free.

Impact:

A remote host may be able to trigger a read of freed kernel memory.

This may trigger a kernel panic if the address had been unmapped.