view src/event/ngx_event_posted.c @ 9286:d9fe808c1841 default tip

HTTP/3: protection from recursion during connection reuse. When draining a connection associated with an HTTP/3 stream, calling ngx_http_v3_send_cancel_stream() might result in an attempt to obtain a connection for the decoder stream. This in turn will trigger draining of the very same connection. Depending on the client settings, this might either lead to stack overflow or will end up in decoder stream creation error and destroying the connection at some point, potentially resulting in use-after-free on stack. Fix is to make sure that connection reuse is disabled in ngx_http_v3_reset_stream(), so the recursion in question won't happen regardless of what called functions do.
author Maxim Dounin <mdounin@mdounin.ru>
date Sun, 02 Jun 2024 23:51:55 +0300
parents f1720934c45b
children
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


ngx_queue_t  ngx_posted_accept_events;
ngx_queue_t  ngx_posted_next_events;
ngx_queue_t  ngx_posted_events;


void
ngx_event_process_posted(ngx_cycle_t *cycle, ngx_queue_t *posted)
{
    ngx_queue_t  *q;
    ngx_event_t  *ev;

    while (!ngx_queue_empty(posted)) {

        q = ngx_queue_head(posted);
        ev = ngx_queue_data(q, ngx_event_t, queue);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                      "posted event %p", ev);

        ngx_delete_posted_event(ev);

        ev->handler(ev);
    }
}


void
ngx_event_move_posted_next(ngx_cycle_t *cycle)
{
    ngx_queue_t  *q;
    ngx_event_t  *ev;

    for (q = ngx_queue_head(&ngx_posted_next_events);
         q != ngx_queue_sentinel(&ngx_posted_next_events);
         q = ngx_queue_next(q))
    {
        ev = ngx_queue_data(q, ngx_event_t, queue);

        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                      "posted next event %p", ev);

        ev->ready = 1;
        ev->available = -1;
    }

    ngx_queue_add(&ngx_posted_events, &ngx_posted_next_events);
    ngx_queue_init(&ngx_posted_next_events);
}