CoreDNS 1.10.1 Return SERVFAIL Error with "dns: overflow unpacking uint16" when Upstream DNS response is more than 512 bytes #5998
Description
What happened:
Use CoreDNS 1.10.1 to query DNS cluster-us-east-1-152269.prevops.com using AzureDNS as upstream DNS server in an AKS cluster. It returns SERVFAIL after ~10 seconds
nslookup cluster-us-east-1-152269.prevops.com.
Server: 10.0.0.10
Address: 10.0.0.10#53
** server can't find cluster-us-east-1-152269.prevops.com: SERVFAIL
What you expected to happen:
It should return a list of IPs
How to reproduce it (as minimally and precisely as possible):
Create an AKS cluster
Change the coredns version to 1.10.1.
Deploy a dnsutils pod, and run nslookup cluster-us-east-1-152269.prevops.com.
Anything else we need to know?:
The issue doesn't repro in 1.10.0, 1.9.4, 1.9.3
Environment:
AKS, AzureDNS
- the version of CoreDNS: 1.10.1
- Corefile:
.:53 {
errors
ready
health {
lameduck 5s
}
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
fallthrough in-addr.arpa ip6.arpa
ttl 30
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
- logs, if applicable:
1.10.1 (Failed)
[INFO] 10.244.1.4:53490 - 19745 "A IN cluster-us-east-1-152269.prevops.com. udp 54 false 512" - - 0 5.001039164s
[ERROR] plugin/errors: 2 cluster-us-east-1-152269.prevops.com. A: dns: overflow unpacking uint16
[INFO] 10.244.1.4:53490 - 19745 "A IN cluster-us-east-1-152269.prevops.com. udp 54 false 512" - - 0 5.001601765s
[ERROR] plugin/errors: 2 cluster-us-east-1-152269.prevops.com. A: dns: overflow unpacking uint16
1.10.0 (Succeeded)
[INFO] 10.244.1.4:39792 - 57873 "A IN cluster-us-east-1-152269.prevops.com. udp 54 false 512" NOERROR qr,aa,tc,rd,ra 2134 0.0001473s
[INFO] 10.244.1.4:39792 - 57873 "A IN cluster-us-east-1-152269.prevops.com. udp 54 false 512" NOERROR qr,aa,tc,rd,ra 2134 0.0001633s
[INFO] 10.244.1.4:45377 - 33354 "A IN cluster-us-east-1-152269.prevops.com. tcp 54 false 65535" NOERROR qr,aa,rd,ra 2134 0.0001247s
[INFO] 10.244.1.4:58169 - 43709 "AAAA IN cluster-us-east-1-152269.prevops.com. tcp 54 false 65535" NOERROR qr,aa,rd,ra 149 0.0000537s
- OS (e.g:
cat /etc/os-release):
PRETTY_NAME="Ubuntu 22.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.2 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy
- Others:
I can provide tcpdump if needed for debugging.