From f2a0946a7aebe46470dd5848191e235576e6f906 Mon Sep 17 00:00:00 2001
From: Pascal Massimino <pascal.massimino@gmail.com>
Date: Wed, 15 Jun 2016 20:54:52 +0200
Subject: [PATCH] add some asserts to delimit the perimeter of CostManager's
 operation

a small protection in a fairly complex code.

Change-Id: I920e10e1fc1c35da2cf486349417048d516ff2b9
---
 src/enc/backward_references.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/enc/backward_references.c b/src/enc/backward_references.c
index b3d4a80d..c7bddcaf 100644
--- a/src/enc/backward_references.c
+++ b/src/enc/backward_references.c
@@ -835,6 +835,7 @@ static WEBP_INLINE void UpdateCost(CostManager* const manager, int i, int index,
                                    double distance_cost) {
   int k = i - index;
   double cost_tmp;
+  assert(k >= 0 && k < MAX_LENGTH);
   cost_tmp = distance_cost + manager->cost_cache_[k];
 
   if (manager->costs_[i] > cost_tmp) {
@@ -1163,6 +1164,7 @@ static int BackwardReferencesHashChainDistanceOnly(
         j_max = 1;
       } else {
         j_max = (int)ceil(cost_manager->min_cost_cache_ / offset_cost);
+        assert(j_max >= 1);
       }
 
       // With the values we currently use for the model, offset_cost is