Red Hat Product Security has been made aware of a Denial of Service vulnerability affecting the DNS implementation of dnsmasq.
Name: Felix Wilhelm (Google Security Team), Fermin J. Serna (Google Security Team), Gabriel Campana (Google Security Team), Kevin Hamacher (Google Security Team), Ron Bowes (Google Security Team)
Versions of dnsmasq shipped with Red Hat Enterprise Linux 6 and 5 do not include the EDNS0 code which includes this flaw.
Further details from the 2.78 pre-release CHANGELOG:
Fix DoS in DNS. Invalid boundary checks in the
add_pseudoheader function allows a memcpy call with negative
size An attacker which can send malicious DNS queries
to dnsmasq can trigger a DoS remotely.
dnsmasq is vulnerable only if one of the following option is
specified: --add-mac, --add-cpe-id or --add-subnet.
Credit to Felix Wilhelm, Fermin J. Serna, Gabriel Campana
and Kevin Hamacher of the Google Security Team for
Created attachment 1330995 [details]
Relevant memcpy call that could be called with negative (type casted to large positive) size was added in this commit:
The first upstream version including this change is 2.76.
Created dnsmasq tracking bugs for this issue:
Affects: fedora-all [bug 1497691]
Google Security Team's repository with test cases:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2017:2836 https://access.redhat.com/errata/RHSA-2017:2836
Red Hat OpenStack Platform includes the dnsmasq-utils RPM which does not contain this flaw's affected code-paths; Red Hat OpenStack Platform is therefore listed as not affected.
However, because all versions of Red Hat OpenStack Platform are based on Red Hat Enterprise Linux, all Red Hat OpenStack Platform users should absolutely upgrade the dnsmasq RPM from Red Hat Enterprise Linux as a matter of urgency using standard update mechanisms (such as 'yum update' or 'openstack overcloud update').