[nginx] Variables: fixed non-indexed access of prefix vars (tick...

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/6c99c5f00fc9
branches:  
changeset: 5815:6c99c5f00fc9
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Wed Aug 27 21:38:04 2014 +0400
description:
Variables: fixed non-indexed access of prefix vars (ticket #600).

Previously, a configuration like

    location / {
        ssi on;
        ssi_types *;
        set $http_foo "bar";
        return 200 '<!--#echo var="http_foo" -->\n';
    }

resulted in NULL pointer dereference in ngx_http_get_variable() as
the variable was explicitly added to the variables hash, but its
get_handler wasn't properly set in the hash.  Fix is to make sure
that get_handler is properly set by ngx_http_variables_init_vars().

diffstat:

 src/http/ngx_http_variables.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (24 lines):

diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -2511,8 +2511,7 @@ ngx_http_variables_init_vars(ngx_conf_t 
 
             av = key[n].value;
 
-            if (av->get_handler
-                && v[i].name.len == key[n].key.len
+            if (v[i].name.len == key[n].key.len
                 && ngx_strncmp(v[i].name.data, key[n].key.data, v[i].name.len)
                    == 0)
             {
@@ -2524,6 +2523,10 @@ ngx_http_variables_init_vars(ngx_conf_t 
 
                 av->index = i;
 
+                if (av->get_handler == NULL) {
+                    break;
+                }
+
                 goto next;
             }
         }