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diff src/core/ngx_resolver.c @ 4619:3171ec7d0d05

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Resolver: protection from duplicate responses. If we already had CNAME in resolver node (i.e. rn->cnlen and rn->u.cname set), and got additional response with A record, it resulted in rn->cnlen set and rn->u.cname overwritten by rn->u.addr (or rn->u.addrs), causing segmentation fault later in ngx_resolver_free_node() on an attempt to free overwritten rn->u.cname. The opposite (i.e. CNAME got after A) might cause similar problems as well.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 14 May 2012 09:13:45 +0000
parents 778d2cc03e22
children bc5f881323b8
line wrap: on
line diff
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -513,8 +513,10 @@ ngx_resolve_name_locked(ngx_resolver_t *
 
         /* lock alloc mutex */
 
-        ngx_resolver_free_locked(r, rn->query);
-        rn->query = NULL;
+        if (rn->query) {
+            ngx_resolver_free_locked(r, rn->query);
+            rn->query = NULL;
+        }
 
         if (rn->cnlen) {
             ngx_resolver_free_locked(r, rn->u.cname);
@@ -1409,6 +1411,9 @@ ngx_resolver_process_a(ngx_resolver_t *r
             ngx_resolver_free(r, addrs);
         }
 
+        ngx_resolver_free(r, rn->query);
+        rn->query = NULL;
+
         return;
 
     } else if (cname) {
@@ -1441,6 +1446,9 @@ ngx_resolver_process_a(ngx_resolver_t *r
             (void) ngx_resolve_name_locked(r, ctx);
         }
 
+        ngx_resolver_free(r, rn->query);
+        rn->query = NULL;
+
         return;
     }