id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
945	when setting master_process off, nginx segmentation fault when sent mutiple HUP singals	tianchaijz@…		"A simple configuration is shown below:

{{{
worker_processes  1;
master_process off;
daemon         off;

events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    sendfile           on;
    keepalive_timeout  65;

    server {
        listen       1200;
        server_name  localhost;

        location / {
            root   html;
            index  index.html index.htm;
        }
    }
}
}}}

After starting nginx process, send multiple HUP signals to it, it will  segmentation fault:
{{{
watch -n 1 'kill -HUP PID'
}}}

After inspecting the core, I found the code dereference a NULL pointer which leads the process segmentation fault:

{{{
(gdb) frame
#0  0x00000000004194e7 in ngx_clean_old_cycles (ev=0x6a5c00 <ngx_cleaner_event>) at src/core/ngx_cycle.c:1313
1313                if (cycle[i]->connections[n].fd != (ngx_socket_t) -1) {
(gdb) bt
#0  0x00000000004194e7 in ngx_clean_old_cycles (ev=0x6a5c00 <ngx_cleaner_event>) at src/core/ngx_cycle.c:1313
#1  0x0000000000425f09 in ngx_event_expire_timers () at src/event/ngx_event_timer.c:94
#2  0x0000000000425b87 in ngx_process_events_and_timers (cycle=cycle@entry=0x1687010) at src/event/ngx_event.c:256
#3  0x000000000042ca91 in ngx_single_process_cycle (cycle=0x1687010, cycle@entry=0x138f480) at src/os/unix/ngx_process_cycle.c:309
#4  0x000000000040c615 in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:364
(gdb) p i
$10 = 1
(gdb) p n
$11 = 0
(gdb) p cycle[1]->connections[0]
Cannot access memory at address 0x0
(gdb) p cycle[1]->connections
$12 = (ngx_connection_t *) 0x0
(gdb)
}}}

{{{
nginx version: nginx/1.9.13
built by gcc 5.3.0 (GCC)
configure arguments: --prefix=/tmp/nginx

Linux tianchaijz 4.4.3-1 #12 SMP PREEMPT Sun Feb 28 17:55:31 CST 2016 x86_64 GNU/Linux
}}}"	defect	closed	minor		documentation	1.9.x	wontfix				"nginx version: nginx/1.9.13
built by gcc 5.3.0 (GCC)
configure arguments: --prefix=/tmp/nginx"