# HG changeset patch
# User Piotr Sikora <piotrsikora@google.com>
# Date 1443756355 25200
# Node ID b6a665bf858a3b614c027ec51f455cddd2a58664
# Parent  22ee99422329070789536dc8914e1b0cae3450db
HTTP/2: fix indirect reprioritization.

Previously, streams that were indirectly reprioritized (either because of
a new exclusive dependency on their parent or because of removal of their
parent from the dependency tree), didn't have their pointer to the parent
node updated.

This broke detection of circular dependencies and, as a result, nginx
worker would crash due to stack overflow whenever such dependency was
introduced.

Found with afl-fuzz.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -2914,11 +2914,14 @@ ngx_http_v2_get_closed_node(ngx_http_v2_
         weight += child->weight;
     }
 
+    parent = node->parent;
+
     for (q = ngx_queue_head(&node->children);
          q != ngx_queue_sentinel(&node->children);
          q = ngx_queue_next(q))
     {
         child = ngx_queue_data(q, ngx_http_v2_node_t, queue);
+        child->parent = parent;
         child->weight = node->weight * child->weight / weight;
 
         if (child->weight == 0) {
@@ -2926,8 +2929,6 @@ ngx_http_v2_get_closed_node(ngx_http_v2_
         }
     }
 
-    parent = node->parent;
-
     if (parent == NGX_HTTP_V2_ROOT) {
         node->rank = 0;
         node->rel_weight = 1.0;
@@ -3940,8 +3941,8 @@ static void
 ngx_http_v2_set_dependency(ngx_http_v2_connection_t *h2c,
     ngx_http_v2_node_t *node, ngx_uint_t depend, ngx_uint_t exclusive)
 {
-    ngx_queue_t         *children;
-    ngx_http_v2_node_t  *parent, *next;
+    ngx_queue_t         *children, *q;
+    ngx_http_v2_node_t  *parent, *child, *next;
 
     parent = depend ? ngx_http_v2_get_node_by_id(h2c, depend, 0) : NULL;
 
@@ -4003,6 +4004,14 @@ ngx_http_v2_set_dependency(ngx_http_v2_c
     }
 
     if (exclusive) {
+        for (q = ngx_queue_head(children);
+             q != ngx_queue_sentinel(children);
+             q = ngx_queue_next(q))
+        {
+            child = ngx_queue_data(q, ngx_http_v2_node_t, queue);
+            child->parent = node;
+        }
+
         ngx_queue_add(&node->children, children);
         ngx_queue_init(children);
     }