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[PATCH] HTTP/2: fixed closed_nodes overflow (ticket #1708)

Maxim Dounin
February 01, 2022 10:30PM
# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1643772371 -10800
# Wed Feb 02 06:26:11 2022 +0300
# Node ID 0b272d5fd6bd0dcca6dcca8f27f8fcde33119159
# Parent dd718d1cef3c2ca2754a21176be3318b00be9e62
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.

diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h
--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -153,12 +153,12 @@ struct ngx_http_v2_connection_s {
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;

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Subject Author Views Posted

[PATCH] HTTP/2: fixed closed_nodes overflow (ticket #1708)

Maxim Dounin 169 February 01, 2022 10:30PM

Re: [PATCH] HTTP/2: fixed closed_nodes overflow (ticket #1708)

Sergey Kandaurov 59 February 03, 2022 12:52PM

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