commit c782ca004ae43af236d67bfb206f22b573edd0a1
author Maxim Dounin <mdounin@mdounin.ru> Thu Feb 03 22:46:01 2022 +0300
committer Maxim Dounin <mdounin@mdounin.ru> Thu Feb 03 22:46:01 2022 +0300
tree c4c08967742632d6b9056bcd94ff6461b993a35c
parent 1bcc8d43d2eed997a5e4c3430459adf63c7657d8

HTTP/2: fixed closed_nodes overflow (ticket #1708).

With large http2_max_concurrent_streams or http2_max_concurrent_pushes, more
than 255 ngx_http_v2_node_t structures might be allocated, eventually leading
to h2c->closed_nodes overflow when closing corresponding streams.  This will
in turn result in additional allocations in ngx_http_v2_get_node_by_id().

While mostly harmless, it can result in excessive memory usage by a HTTP/2
connection, notably in configurations with many keepalive_requests allowed.
Fix is to use ngx_uint_t for h2c->closed_nodes instead of unsigned:8.

src/http/v2/ngx_http_v2.h

diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h
index 70ee287..4e25293 100644
--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -153,12 +153,12 @@
     ngx_queue_t                      dependencies;
     ngx_queue_t                      closed;
 
+    ngx_uint_t                       closed_nodes;
     ngx_uint_t                       last_sid;
     ngx_uint_t                       last_push;
 
     time_t                           lingering_time;
 
-    unsigned                         closed_nodes:8;
     unsigned                         settings_ack:1;
     unsigned                         table_update:1;
     unsigned                         blocked:1;