From 123cab757af12791b05f7935135075afaab08e23 Mon Sep 17 00:00:00 2001
From: Li Tan <lit@fb.com>
Date: Thu, 8 Jan 2015 11:49:31 -0800
Subject: [PATCH] Add safety check to avoid crash in ASFlowLayoutController

---
 AsyncDisplayKit/Details/ASFlowLayoutController.mm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/AsyncDisplayKit/Details/ASFlowLayoutController.mm b/AsyncDisplayKit/Details/ASFlowLayoutController.mm
index 115b38a0e1..26bed9eb83 100644
--- a/AsyncDisplayKit/Details/ASFlowLayoutController.mm
+++ b/AsyncDisplayKit/Details/ASFlowLayoutController.mm
@@ -153,7 +153,7 @@ static const std::pair<int, int> ASFindIndexForRange(const std::vector<std::vect
                                                      ASFlowLayoutDirection layoutDirection) {
   std::pair<int, int> cur = pos, pre = pos;
 
-  if (range < 0.0 && cur.first >= 0 && cur.second >= 0) {
+  if (range < 0.0 && cur.first >= 0 && cur.first < nodes.size() && cur.second >= 0 && cur.second < nodes[cur.first].size()) {
     // search backward
     while (range < 0.0 && cur.first >= 0 && cur.second >= 0) {
       pre = cur;
@@ -170,7 +170,7 @@ static const std::pair<int, int> ASFindIndexForRange(const std::vector<std::vect
     }
   } else {
     // search forward
-    while (range > 0.0 && cur.first < nodes.size() && cur.second < nodes[cur.first].size()) {
+    while (range > 0.0 && cur.first >= 0 && cur.first < nodes.size() && cur.second >= 0 && cur.second < nodes[cur.first].size()) {
       pre = cur;
       CGSize size = nodes[cur.first][cur.second];
       range -= layoutDirection == ASFlowLayoutDirectionHorizontal ? size.width : size.height;