Bug 1566983

Created attachment 1421280 [details]
0001-add-child-reaper-thread-to-fix-zombies

Description of problem:

When subprocess running timeout in rules , the subprocess will be zombie. 

The utils_spawn_data_free reap timeout subprocess did not work , and it result in a large number of zombie processes. utils_spawn_data_free kill SIGTERM to timeout subprocess, and set a child watch source to reap the child, but the child watch source can't work because of the release of it's main_loop and context outside. 

I paste  the key code here.
static void 
js_polkit_spawn()
{
  ...
 out:
  g_strfreev (argv);
  g_free (standard_output);
  g_free (standard_error);
  g_clear_object (&data.res); // triger utils_spawn_data_free  and set child watch source 
  if (loop != NULL)
    g_main_loop_unref (loop); // destroy loop 
  if (context != NULL)
    g_main_context_unref (context);// destroy context
  return ret;
}

When the loop and context being destroy, the child watch source didn't work. subprocess exit and become a zombie.


Version-Release number of selected component (if applicable):
polkitd all version

How reproducible:
100%

Steps to Reproduce:
1.  Add a debug rule , this rule waill run spawn process over 10s and result in a timeout
[root@localhost ~]# cat /etc/polkit-1/rules.d/01-test.rules   
 polkit.addRule(function(action, subject) {             
        polkit.log("debug start")                       
         try {                                          
             polkit.spawn(["/usr/bin/sleep", "15"]);       
         } catch (error) {                              
             //    polkit.log(error)                    
         }                                              
 });                                                    
2. make the rules work
3. 

Actual results:
subprocess become zombie

Expected results:
no zombies

Additional info:

[root@localhost ~]# ps -ef |grep polkit |grep -v polkit
polkitd   1501     1  0 Mar31 ?        00:02:51 /usr/lib/polkit-1/polkitd --no-debug
polkitd   5060  1501  0 12:37 ?        00:00:00 [sleep] <defunct>
polkitd   5367  1501  0 12:38 ?        00:00:00 [sleep] <defunct>
polkitd   5631  1501  0 12:38 ?        00:00:00 [sleep] <defunct>
polkitd   5915  1501  0 12:38 ?        00:00:00 [sleep] <defunct>
polkitd  14052  1501  0 12:42 ?        00:00:00 sleep 15

[root@localhost ~]# journalctl -fu polkit
-- Logs begin at Sat 2018-03-31 14:36:03 CST. --
Apr 03 12:39:11 2-3 polkitd[1501]: /etc/polkit-1/rules.d/01-test.rules:5: Error: Error spawning helper: Timed out after 10 seconds (g-io-error-quark, 24)
Apr 03 12:39:21 2-3 polkitd[1501]: /etc/polkit-1/rules.d/01-test.rules:5: Error: Error spawning helper: Timed out after 10 seconds (g-io-error-quark, 24)
Apr 03 12:40:11 2-3 polkitd[1501]: /etc/polkit-1/rules.d/01-test.rules:5: Error: Error spawning helper: Timed out after 10 seconds (g-io-error-quark, 24)
Apr 03 12:40:21 2-3 polkitd[1501]: /etc/polkit-1/rules.d/01-test.rules:5: Error: Error spawning helper: Timed out after 10 seconds (g-io-error-quark, 24)