crash in ngx_add_timer

胡聪 (hucc) hucong.c at foxmail.com
Wed Apr 19 02:30:23 UTC 2017


That`s right! I almost forgot that.




------------------ Original ------------------
From:  "734819342";<734819342 at qq.com>;
Send time: Wednesday, Apr 19, 2017 10:23 AM
To: "nginx-devel at nginx.org"<nginx-devel at nginx.org>; 

Subject:  Re: crash in ngx_add_timer




Hi,




    U should not call ngx_add_timer there, cause ngx_event_timer_rbtree is initialized in [init process].



----------------------------

Ben
best regards










                             Original Message                             
Sender: Dk Jack<dnj0496 at gmail.com>
Recipient: nginx-devel at nginx.org<nginx-devel at nginx.org>
Date: Wednesday, Apr 19, 2017?10:03
Subject: Re: crash in ngx_add_timer


  Hi, The crash is happening at line: 
 
 ngx_add_timer(&ev2, 6);    // line 81
 
 
 
 i.e. when it's trying to insert the second time. It doesn't even get to the handler.
 
 
 
 What would be a good value to assign to ev->log? I added:
 
 
 ev->log = cf->cycle->log
 
 
 I am still getting the crash when I try to insert the second timer.
 
 On Tue, Apr 18, 2017 at 6:53 PM, 胡聪 (hucc)  <hucong.c at foxmail.com> wrote:
  Hi,
 
 
 At the first glance, the ev->log should be assigned a valid value.
  
 
 
 
 ------------------ Original ------------------
  From:  "Dk Jack";<dnj0496 at gmail.com>;
 Send time: Wednesday, Apr 19, 2017 8:23 AM
 To: "nginx-devel"<nginx-devel at nginx.org>; 
 
 Subject:  Re: crash in ngx_add_timer
 
   
 
 resending since the attachment which had the code didn't make it... 
 
 Dk.
 
 
  #include <assert.h>
 #include <nginx.h>
 #include <ngx_config.h>
 #include <ngx_core.h>
 #include <ngx_http.h>
 
 
 static ngx_event_t ev1;
 static ngx_event_t ev2;
 static ngx_event_t ev3;
 
 
 char ev1_data[] = "event1";
 char ev2_data[] = "event2";
 char ev3_data[] = "event3";
 
 
 static ngx_int_t
 ngx_test_handler(ngx_http_request_t *r)
 {
   if (r->main->internal) {
     return NGX_DECLINED;
   }
 
 
   r->main->internal = 1;
 
 
   ngx_table_elt_t *h;
   h = ngx_list_push(&r->headers_out.headers);
   h->hash = 1;
   ngx_str_set(&h->key, "X-NGINX-Test");
   ngx_str_set(&h->value, "Hello World!");
 
 
   return NGX_DECLINED;
 }
 
 
 static void
 ev1_handler(ngx_event_t* ev)
 {
   ngx_log_error(NGX_LOG_ERR, ev->log, 0, "received event: %s", (char *) ev->data);
   ngx_add_timer(&ev1, 5);
 }
 
 
 static void
 ev2_handler(ngx_event_t* ev)
 {
   ngx_log_error(NGX_LOG_ERR, ev->log, 0, "received event: %s", (char *) ev->data);
   ngx_add_timer(&ev2, 6);
 }
 
 
 static void
 ev3_handler(ngx_event_t* ev)
 {
   ngx_log_error(NGX_LOG_ERR, ev->log, 0, "received event: %s", (char *) ev->data);
   ngx_add_timer(&ev3, 7);
 }
 
 
 static ngx_int_t
 ngx_test_init (ngx_conf_t *cf)
 {
   ngx_http_handler_pt *h;
   ngx_http_core_main_conf_t *cmcf;
 
 
   cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
   h = ngx_array_push(&cmcf->phases[NGX_HTTP_ACCESS_PHASE].handlers);
 
 
   if (h == NULL) {
     ngx_log_error(NGX_LOG_ERR, cf->log, 0, "Cannot retrieve Nginx access handler pointer");
     return NGX_ERROR;
   }
 
 
   *h = ngx_test_handler;
   ngx_log_error(NGX_LOG_INFO, cf->log, 0, "[test] Installed test handler");
 
 
   ev1.handler = ev1_handler;
   ev1.data = ev1_data;
 
 
   ev2.handler = ev2_handler;
   ev2.data = ev2_data;
 
 
   ev3.handler = ev3_handler;
   ev3.data = ev3_data;
 
 
   ngx_add_timer(&ev1, 5);
   ngx_add_timer(&ev2, 6);
   ngx_add_timer(&ev3, 7);
 
 
   return NGX_OK;
 }
 
 
 static char *
 parse_test_configuration (ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
   ngx_str_t *value;
 
 
   if (cf->args->nelts != 2) {
     ngx_log_error(NGX_LOG_ERR, cf->log, 0
                   , "[ss-config] invalid params for config_file. Expected 2 received %d"
                   , cf->args->nelts);
     return NGX_CONF_ERROR;
   }
 
 
   value = cf->args->elts;
 
 
   ngx_log_error(NGX_LOG_ERR, cf->log, 0, "file-path: %V", &value[1]);
 
 
   return NGX_CONF_OK;
 }
 
 
 
 
 static ngx_http_module_t ngx_test_module_ctx = {
   NULL,                                 /* preconfiguration */
   ngx_test_init,               /* postconfiguration */
   NULL,                                 /* create main configuration */
   NULL,                                 /* init main configuration */
   NULL,                                 /* create server configuration */
   NULL,                                 /* merge server configuration */
   NULL,        /* create location configuration */
   NULL          /* merge location configuration */
 };
 
 
 static ngx_command_t ngx_test_module_cmds[] = {
   {
     ngx_string("config_file"),
     NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
     parse_test_configuration,
     0,
     0,
     NULL
   }
   , ngx_null_command
 };
 
 
 ngx_module_t nginx_test_module = {
   NGX_MODULE_V1,
   &ngx_test_module_ctx,   /* module context */
   ngx_test_module_cmds,   /* module directives */
   NGX_HTTP_MODULE,                 /* module type */
   NULL,                            /* init master */
   NULL,                            /* init module */
   NULL,                            /* init process */
   NULL,                            /* init thread */
   NULL,                            /* exit thread */
   NULL,                            /* exit process */
   NULL,                            /* exit master */
   NGX_MODULE_V1_PADDING
 };
 
 
 
 On Tue, Apr 18, 2017 at 5:12 PM, Dk Jack  <dnj0496 at gmail.com> wrote:
  Hi, I am new to NGinx modules and I trying to write an nginx module. I am having an issue
 where my module crashes when adding multiple timers. The first timer adds fine.
 However, when I go to add the second timer, it crashes. I've simplified the code to a very
 basic module (which is attached to this email). The backtrace is provided as well.
 Do I need to do some sort of initialization before I add multiple timers. Any advice/help
 is appreciated. Thanks.
 
 
 Dk.
 
 
  Program received signal SIGSEGV, Segmentation fault.
 0x0000000000000000 in ?? ()
 (gdb) bt
 #0  0x0000000000000000 in ?? ()
 #1  0x000000000040d68b in ngx_rbtree_insert (tree=0x69dda0 <ngx_event_timer_rbtree>,
     node=node at entry=0x69db08 <ev2+40>) at src/core/ngx_rbtree.c:44
 #2  0x000000000046ceb2 in ngx_event_add_timer (timer=6, ev=0x69dae0 <ev2>)
     at src/event/ngx_event_timer.h:84
 #3  ngx_test_init (cf=<optimized out>)
     at /home/ubuntu/git/mitigator/nginx/build/../modules/nginx_mitigator_module/platform/nginx-test-module.c:81
 #4  0x0000000000424e83 in ngx_http_block (cf=0x7fffffffe0a0, cmd=<optimized out>,
     conf=<optimized out>) at src/http/ngx_http.c:315
 #5  0x000000000041446b in ngx_conf_handler (last=1, cf=0x7fffffffe0a0)
     at src/core/ngx_conf_file.c:427
 #6  ngx_conf_parse (cf=cf at entry=0x7fffffffe0a0, filename=filename at entry=0x6ad570)
     at src/core/ngx_conf_file.c:283
 #7  0x0000000000411e1a in ngx_init_cycle (old_cycle=old_cycle at entry=0x7fffffffe260)
     at src/core/ngx_cycle.c:268
 #8  0x0000000000404208 in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:268
 (gdb)
 
 
  
 
 
 
 
 
 
 
 
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