From 1748e52e41b7bd8bde8cc917053c39bd6849c17d Mon Sep 17 00:00:00 2001
From: Cosmin Truta <ctruta@gmail.com>
Date: Sun, 17 Jun 2018 22:56:29 -0400
Subject: [PATCH] Fix the calculation of row_factor in png_check_chunk_length

(Bug report by Thuan Pham, SourceForge issue #278)
---
 pngrutil.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/pngrutil.c b/pngrutil.c
index d5a344d..1e90863 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -2839,10 +2839,13 @@ png_check_chunk_length(png_structp png_ptr, png_uint_32 length)
    {
       png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
       size_t row_factor =
-         (png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
-          + 1 + (png_ptr->interlaced? 6: 0));
+         (size_t)png_ptr->width
+         * (size_t)png_ptr->channels
+         * (png_ptr->bit_depth > 8? 2: 1)
+         + 1
+         + (png_ptr->interlaced? 6: 0);
       if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
-         idat_limit=PNG_UINT_31_MAX;
+         idat_limit = PNG_UINT_31_MAX;
       else
          idat_limit = png_ptr->height * row_factor;
       row_factor = row_factor > 32566? 32566 : row_factor;
-- 
2.17.1