Specifying "max-cache-size default;" causes core-dump

Hi list.

I've tried to raise a new issue for BIND on 
https://gitlab.isc.org/isc-projects/bind9/-/issues but unfortunately 
when I click "Create issue", it pops up a banner saying: /Your issue has 
been recognized as spam. Please, change the content or solve the 
reCAPTCHA to proceed./

...And no reCAPTCHA code is displayed.

So I hope it's OK if I report the issue to this list instead?

Thanks,

Nick.

------------------------------------------------------------------------

*/Specifying "max-cache-size default;" causes core-dump/*

*### Summary*

Specifying `max-cache-size default;` in the configuration causes an 
assertion failure.

*### BIND version affected*

The BIND versions that I've tested are 9.20.4 (included with Linux 
distro) and 9.20.14 (i.e. downloaded and compiled latest version).

```
BIND 9.20.14-dev (Stable Release) <id:1cbd8b8>
running on Linux x86_64 6.14.0-29-generic #29-Ubuntu SMP PREEMPT_DYNAMIC Thu Aug  7 18:32:38 UTC 2025
built by make with default
compiled by GCC 14.2.0
compiled with OpenSSL version: OpenSSL 3.4.1 11 Feb 2025
linked to OpenSSL version: OpenSSL 3.4.1 11 Feb 2025
compiled with libuv version: 1.50.0
linked to libuv version: 1.50.0
compiled with liburcu version: 0.15.1
compiled with jemalloc version: 5.3.0
compiled with libnghttp2 version: 1.64.0
linked to libnghttp2 version: 1.64.0
compiled with zlib version: 1.3.1
linked to zlib version: 1.3.1
threads support is enabled
DNSSEC algorithms: RSASHA1 NSEC3RSASHA1 RSASHA256 RSASHA512 ECDSAP256SHA256 ECDSAP384SHA384 ED25519 ED448
DS algorithms: SHA-1 SHA-256 SHA-384
HMAC algorithms: HMAC-MD5 HMAC-SHA1 HMAC-SHA224 HMAC-SHA256 HMAC-SHA384 HMAC-SHA512
TKEY mode 2 support (Diffie-Hellman): no
TKEY mode 3 support (GSS-API): no
default paths:
   named configuration:  /usr/local/etc/named.conf
   rndc configuration:   /usr/local/etc/rndc.conf
   nsupdate session key: /usr/local/var/run/named/session.key
   named PID file:       /usr/local/var/run/named/named.pid
```


*### Steps to reproduce*

1. Use configuration file below.
2. Start BIND server with command: `named -g -c named.conf ...`

*### What is the current *bug* behavior?*

BIND core-dumps and exits.

*### What is the expected *correct* behavior?*

BIND should use the default setting for max-cache-size according to the 
[documentation](https://bind9.readthedocs.io/en/stable/reference.html#namedconf-statement-max-cache-size):

 > The default size limit for each individual cache is:
 > * 90% of physical memory for views with recursion set to yes (the 
default), or
 > * 2 MB for views with recursion set to no.

*### Relevant configuration files*

named.conf

```
controls {};
options {
     forward only;
     forwarders { ::1; };
     listen-on port 8053 { 127.0.0.1; };
     listen-on-v6 port 8053 { ::1; };
     max-cache-size default;
     empty-zones-enable no;
     session-keyfile "session.key";
};
logging {
     category default { default_debug; };
     category unmatched { null; };
};
```


*### Relevant logs*

```
14-Sep-2025 13:33:24.314 starting BIND 9.20.14-dev (Stable Release) <id:1cbd8b8>
14-Sep-2025 13:33:24.314 running on Linux x86_64 6.14.0-29-generic #29-Ubuntu SMP PREEMPT_DYNAMIC Thu Aug  7 18:32:38 UTC 2025
14-Sep-2025 13:33:24.314 built with default
14-Sep-2025 13:33:24.314 running as: named -g -n 1 -c named.conf
14-Sep-2025 13:33:24.314 compiled by GCC 14.2.0
14-Sep-2025 13:33:24.314 compiled with OpenSSL version: OpenSSL 3.4.1 11 Feb 2025
14-Sep-2025 13:33:24.314 linked to OpenSSL version: OpenSSL 3.4.1 11 Feb 2025
14-Sep-2025 13:33:24.314 compiled with libuv version: 1.50.0
14-Sep-2025 13:33:24.314 linked to libuv version: 1.50.0
14-Sep-2025 13:33:24.314 compiled with liburcu version: 0.15.1
14-Sep-2025 13:33:24.314 compiled with jemalloc version: 5.3.0
14-Sep-2025 13:33:24.314 compiled with libnghttp2 version: 1.64.0
14-Sep-2025 13:33:24.314 linked to libnghttp2 version: 1.64.0
14-Sep-2025 13:33:24.314 compiled with zlib version: 1.3.1
14-Sep-2025 13:33:24.314 linked to zlib version: 1.3.1
14-Sep-2025 13:33:24.314 ----------------------------------------------------
14-Sep-2025 13:33:24.314 BIND 9 is maintained by Internet Systems Consortium,
14-Sep-2025 13:33:24.314 Inc. (ISC), a non-profit 501(c)(3) public-benefit
14-Sep-2025 13:33:24.314 corporation.  Support and training for BIND 9 are
14-Sep-2025 13:33:24.314 available athttps://www.isc.org/support
14-Sep-2025 13:33:24.314 ----------------------------------------------------
14-Sep-2025 13:33:24.314 adjusted limit on open files from 1024 to 1073741816
14-Sep-2025 13:33:24.314 found 8 CPUs, using 1 worker thread
14-Sep-2025 13:33:24.316 DNSSEC algorithms: RSASHA1 NSEC3RSASHA1 RSASHA256 RSASHA512 ECDSAP256SHA256 ECDSAP384SHA384 ED25519 ED448
14-Sep-2025 13:33:24.316 DS algorithms: SHA-1 SHA-256 SHA-384
14-Sep-2025 13:33:24.316 HMAC algorithms: HMAC-MD5 HMAC-SHA1 HMAC-SHA224 HMAC-SHA256 HMAC-SHA384 HMAC-SHA512
14-Sep-2025 13:33:24.316 TKEY mode 2 support (Diffie-Hellman): no
14-Sep-2025 13:33:24.316 TKEY mode 3 support (GSS-API): no
14-Sep-2025 13:33:24.317 the initial working directory is '/home/nick/Development/opensource/bind9/nick'
14-Sep-2025 13:33:24.317 loading configuration from '/home/nick/Development/opensource/bind9/nick/named.conf'
14-Sep-2025 13:33:24.317 using default UDP/IPv4 port range: [32768, 60999]
14-Sep-2025 13:33:24.317 using default UDP/IPv6 port range: [32768, 60999]
14-Sep-2025 13:33:24.318 listening on IPv4 interface lo, 127.0.0.1#8053
14-Sep-2025 13:33:24.318 listening on IPv6 interface lo, ::1#8053
14-Sep-2025 13:33:24.318 Disabling periodic interface re-scans timer
14-Sep-2025 13:33:24.318 couldn't mkdir '/usr/local/var': Permission denied
14-Sep-2025 13:33:24.318 generating session key for dynamic DNS
14-Sep-2025 13:33:24.319 server.c:4480: INSIST(strcasecmp(str, "unlimited") == 0) failed
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/lib/isc/.libs/libisc-9.20.14-dev.so(isc_backtrace_log+0x3f) [0x74a24afa5d3f]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(+0x278bb) [0x615c2e0348bb]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/lib/isc/.libs/libisc-9.20.14-dev.so(isc_assertion_failed+0x10) [0x74a24afa5890]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(+0x3bf3b) [0x615c2e048f3b]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(+0x4a01a) [0x615c2e05701a]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(+0x4ad3d) [0x615c2e057d3d]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/lib/isc/.libs/libisc-9.20.14-dev.so(isc__async_cb+0xa7) [0x74a24afa5bd7]
14-Sep-2025 13:33:24.319 /lib/x86_64-linux-gnu/libuv.so.1(+0xb933) [0x74a24ae9d933]
14-Sep-2025 13:33:24.319 /lib/x86_64-linux-gnu/libuv.so.1(+0x2bd9c) [0x74a24aebdd9c]
14-Sep-2025 13:33:24.319 /lib/x86_64-linux-gnu/libuv.so.1(uv_run+0x247) [0x74a24aeaaa47]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/lib/isc/.libs/libisc-9.20.14-dev.so(+0x4c17e) [0x74a24afb917e]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(main+0xe02) [0x615c2e028ab2]
14-Sep-2025 13:33:24.319 /lib/x86_64-linux-gnu/libc.so.6(+0x2a578) [0x74a24a22a578]
14-Sep-2025 13:33:24.319 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x8b) [0x74a24a22a63b]
14-Sep-2025 13:33:24.319 /home/nick/Development/opensource/bind9/bin/named/.libs/named(_start+0x25) [0x615c2e0294c5]
14-Sep-2025 13:33:24.319 exiting (due to assertion failure)
Aborted (core dumped)
```


/label ~Bug

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