Hash mismatch with out-of-order enums ≥32

[mattiaswal]

Summary

I have tried to root cause this. As far as I have understood it, when augmenting IETF standard modules (ietf-interfaces, ietf-ip) with enumerations that have:

1. Values declared out of ascending order
2. Values ≥32 being set
3. Active sysrepo subscriptions (running & candidate), it is sysrepo-plugind that crashes.

In the log i get Failed to find matching hash for a top-level node from "sysrepo-notifications".

Environment

• libyang version: 4.2.x (master with all commits on devel marked BUGFIX)
• sysrepo version: 4.2.10
• System: Infix Linux embedded system

Minimal YANG Reproducer

module test-augment-enum-order {
  yang-version 1.1;
  namespace "urn:test:augment-enum-order";
  prefix test;

  import ietf-interfaces { prefix if; }
  import ietf-ip { prefix ip; }

  description "Reproducer for LYB hash bug with out-of-order enums";

  augment "/if:interfaces/if:interface/ip:ipv6" {
    container test-order {
      presence "Test out-of-order enums";

      leaf test-value {
        type enumeration {
          enum value-1 { value 1; }
          enum value-56 { value 56; }
          enum value-25 { value 25; }
          enum value-39 { value 39; }
          enum value-32 { value 32; }
          enum value-31 { value 31; }
        }
      }
    }
  }
}

Note: Enums are declared out of order: 1, 56, 25, 39, 32, 31

1,25,31 will pass, the rest fail.

It is also possible to reproduce in infix (virtual x86_64), commit c56a9f2c0ea2873329d9eb75e3a44d320a1287af, by setting admin@bpi-26-60-00:/config/interface/e1/ipv6/> set dhcp option ntp-server
(value 56)

Trigger the bug via netopeer2 (2.7.0)

# Connect to NETCONF server
netopeer2-cli
> connect --host localhost --login admin

# Edit candidate with high enum value (≥32)
> edit-config --target candidate --config=/tmp/test.xml
> commit

test.xml:

<interfaces xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces">
  <interface>
    <name>eth0</name>
    <ipv6 xmlns="urn:ietf:params:xml:ns:yang:ietf-ip">
      <test-order xmlns="urn:test:augment-enum-order">
        <test-value>value-56</test-value>
      </test-order>
    </ipv6>
  </interface>
</interfaces>

Workaround

Reorder enumeration declarations to ascending order by value:

type enumeration {
  enum value-1 { value 1; }
  enum value-25 { value 25; }
  enum value-31 { value 31; }
  enum value-32 { value 32; }
  enum value-39 { value 39; }
  enum value-56 { value 56; }
}

After reordering, all values work correctly, but it feels a little shaky.