russell@unturf.com 9934133dcf whitepaper: 312 sites / 151 ecosystems — wave2+3 defect tables and PDF rebuild

Add 88 new defect entries to HIGH and MEDIUM tables:
  HIGH: mysql-0001/0002, mariadb-0001, redis-0001/0002, valkey-0001/0002, openvpn-0001,
        vlc-0001, prometheus-0001, otel-collector-0001, cockroachdb-0001..0004,
        tidb-0001..0008, kubernetes-0001/0002, go-0001, kotlin-0002, scala-0001,
        allegro5-0001, sdl2-0001, grafana-0001, clickhouse-0001, duckdb-0001,
        mongodb-0001, envoy-0001, istio-0001, cilium-0001, linkerd2-0001,
        linux-0001/0002/0003, tor-0002/0003, curl-0001, julia-0001, lua-0001,
        perl5-0001, nats-0001, spring-0003/0004, tomcat-0001, onos-0002, odl-0002

  MEDIUM: helm-0001, mariadb-0002, openssl-0001/0002, memcached-0001,
          cassandra-0001..0004, flink-0001, storm-0001/0002, zookeeper-0001..0003,
          pip-0001, gradle-0001, nginx-0001, haproxy-0001, caddy-0001, varnish-0001,
          ffmpeg-0001, gstreamer-0001, raylib-0001, love2d-0001, php-0001/0002,
          r-source-0001, cpython-0002, ruby-0001, rabbitmq-0003/0004, activemq-0001,
          ovs-0001, onos-0003, odl-0002, jetty-0001

PDF: 976K

2026-03-27 15:23:43 -04:00

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nginx-0001: ngx_http_upstream_cache_get linear cache-zone name scan

Target: nginx File: src/http/ngx_http_upstream.c Function: ngx_http_upstream_cache_get Lines: 1058–1069 Severity: MEDIUM CWE: CWE-407 (Inefficient Algorithmic Complexity)

Description

When a proxy_cache directive uses a variable ($variable) rather than a literal zone name, nginx resolves the zone on every request by walking the u->caches array with ngx_strncmp comparisons. With N configured cache zones and R requests per second the total work is O(N × R).

caches = u->caches->elts;

for (i = 0; i < u->caches->nelts; i++) {
    name = &caches[i]->shm_zone->shm.name;

    if (name->len == val.len
        && ngx_strncmp(name->data, val.data, val.len) == 0)
    {
        *cache = caches[i];
        return NGX_OK;
    }
}

Impact

Real-world configs with multiple cache zones (e.g. tiered caching, per-vhost zones) make this a hot O(N) scan on every cacheable proxy request.
N is bounded by the number of proxy_cache_zone directives (typically 2–8), but the scan repeats for every request where proxy_cache is a variable.

Fix

Build a hash map from zone name → ngx_http_file_cache_t * at configuration time. At request time use ngx_hash_find (O(1)) instead of the linear scan. The map key is the shm zone name (ASCII, lowercase-normalizable).

Patch

See defects/nginx/patch/nginx-0001.patch

Unit Test

See defects/nginx/unit/NginxCacheGetAlgorithmTest.java

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