Resolver: fixed use-after-free memory access.

In 954867a2f0a6, we switched to using resolver node as the
timer event data, so make sure we do not free resolver node
memory until the corresponding timer is deleted.

diff --git a/src/core/ngx_resolver.c b/src/core/ngx_resolver.c
index a17793b13c7e5458641770e3d4f269beaccfe9c4..7aa20ea678d6f58840d318380dcfbdc4a38ed761 100644 (file)
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -1568,8 +1568,6 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
 
         ngx_rbtree_delete(&r->name_rbtree, &rn->node);
 
-        ngx_resolver_free_node(r, rn);
-
         /* unlock name mutex */
 
         while (next) {
@@ -1580,6 +1578,8 @@ ngx_resolver_process_a(ngx_resolver_t *r, u_char *buf, size_t last,
             ctx->handler(ctx);
         }
 
+        ngx_resolver_free_node(r, rn);
+
         return;
     }
 
@@ -2143,8 +2143,6 @@ valid:
 
         ngx_rbtree_delete(tree, &rn->node);
 
-        ngx_resolver_free_node(r, rn);
-
         /* unlock addr mutex */
 
         while (next) {
@@ -2155,6 +2153,8 @@ valid:
             ctx->handler(ctx);
         }
 
+        ngx_resolver_free_node(r, rn);
+
         return;
     }