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+++ This bug was initially created as a clone of Bug #1921152 +++ Description of problem: In fix of CVE-2020-25686 was created regression, which applies when multiple address families send request for the same name. In that case, only one family receives responses. Version-Release number of selected component (if applicable): dnsmasq-2.83-1.fc33 How reproducible: 100% Steps to Reproduce: 1. send multiple ipv4 requests for one name 2. send multiple ipv6 requests for the same name 3. both address families join single request Actual results: Only half of responses arrives, one address family will not receive Expected results: Both address families receive all responses. Additional info: Discovered after new upstream release, reported on mailing list[1]. Fixed by release of dnsmasq-2.84 1. https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014613.html
Possible workaround is reducing priority of one family, for example IPv6. If most clients query using the same family, this error would not be visible. It would show only when both IPv4 and IPv6 is used for the same name.
Another workaround would be serving each address family from different dnsmasq instance. dnsmasq --bind-interfaces --listen-address=<local-ipv4-address> ... dnsmasq --bind-interfaces --listen-address=<local-ipv6-address> ... Operating multiple instances usually requires more work. Some port redirection might work as well, listening on IPv6 socket and forwarding to ipv4. It would lose source address infromation that way, only localhost would be in logs.
Fixed by: http://pkgs.devel.redhat.com/cgit/rpms/dnsmasq/commit/?h=rhel-8.5.0&id=b958ffb06fa88459e28c2c8893ba5f6ece7d04df http://pkgs.devel.redhat.com/cgit/rpms/dnsmasq/commit/?h=rhel-8.5.0&id=4989893da935bedc06ff14119098e2e01159cd2c
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Moderate: dnsmasq security and bug fix update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2021:4153