[Varnish] #878: Varnish child dies with segfault when loading a VCL importing std vmod

[Varnish]

#878: Varnish child dies with segfault when loading a VCL importing std vmod
----------------------+-----------------------------------------------------
 Reporter:  tmagnien  |       Owner:  phk              
     Type:  defect    |      Status:  new              
 Priority:  normal    |   Milestone:                   
Component:  varnishd  |     Version:  trunk            
 Severity:  normal    |    Keywords:  std vmod segfault
----------------------+-----------------------------------------------------

Comment(by tmagnien):

 I made further investigations and here is what I found.

 In the generated VCL code, we have this function :


 {{{
 static void
 VGC_Init(struct cli *cli)
 {

         VRT_Vmod_Init(&VGC_vmod_std,
             &Vmod_Func_std,
             sizeof(Vmod_Func_std),
             "std",
             "/usr/local/unmodified/lib/varnish/vmods/libvmod_std.so");
         Vmod_Func_std._init(&vmod_priv_std, &VCL_conf);
         VRT_init_dir(cli, VCL_conf.director, "simple",
             VGC_backend__default, &vgc_dir_priv__default);
         VCL_conf.director[0] = VCL_conf.director[1];
 }

 }}}

 What happens is that the 1st time the VCL is loaded (at startup for
 example), the Vmod_Func_std is filled by the VRT_Vmod_Init function. The
 second time the VCL is loaded (by a vcl.load), the VRT_Vmod_Init function
 is called with a Vmod_Func_std pointer value which is different. BUT, the
 VRT_Vmod_Init starts with :


 {{{
         VTAILQ_FOREACH(v, &vmods, list)
                 if (!strcmp(v->nm, nm))
                         break;

 }}}

 And as the std vmod is already loaded, it breaks. So the Vmod_Func_std is
 not populated, so value of Vmod_Func_std._init is NULL, which causes the
 segfault.

 Now I'll try to find the right way to correct this, without loading std
 vmod twice...

 Regards,
 Thierry

-- 
Ticket URL: <http://www.varnish-cache.org/trac/ticket/878#comment:2>
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