--- /dev/null
+# HG changeset patch
+# User Bob Friesenhahn <bfriesen@GraphicsMagick.org>
+# Date 1590851896 18000
+# Sat May 30 10:18:16 2020 -0500
+# Node ID 50395430a37188d0d197e71bd85ed6dd0f649ee3
+# Parent 4917a4242fc0a12f2f6baa10f1c5a9b3e68c20dd
+MNG: Fix small heap overwrite or assertion if magnifying and image to be magnified has rows or columns == 1.
+
+[Retrieved (and updated to remove ChangeLog and version changes) from:
+https://sourceforge.net/p/graphicsmagick/code/ci/50395430a37188d0d197e71bd85ed6dd0f649ee3]
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+
+diff -r 4917a4242fc0 -r 50395430a371 coders/png.c
+--- a/coders/png.c Fri May 01 13:49:13 2020 -0500
++++ b/coders/png.c Sat May 30 10:18:16 2020 -0500
+@@ -5304,7 +5304,7 @@
+ if (logging)
+ (void) LogMagickEvent(CoderEvent,GetMagickModule(),
+ "MAGN chunk (%lu bytes): "
+- "First_magnified_object_id=%u, Last_magnified_object_id=%u, "
++ "First_magnified_object_id=%u, Las t_magnified_object_id=%u, "
+ "MB=%u, ML=%u, MR=%u, MT=%u, MX=%u, MY=%u, "
+ "X_method=%u, Y_method=%u",
+ length,
+@@ -5679,6 +5679,8 @@
+ /*
+ If magnifying and a supported method is requested then
+ magnify the image.
++
++ http://www.libpng.org/pub/mng/spec/mng-1.0-20010209-pdg.html#mng-MAGN
+ */
+ if (((mng_info->magn_methx > 0) && (mng_info->magn_methx <= 5)) &&
+ ((mng_info->magn_methy > 0) && (mng_info->magn_methy <= 5)))
+@@ -5689,7 +5691,28 @@
+
+ if (logging)
+ (void) LogMagickEvent(CoderEvent,GetMagickModule(),
+- " Processing MNG MAGN chunk");
++ " Processing MNG MAGN chunk: MB=%u, ML=%u,"
++ " MR=%u, MT=%u, MX=%u, MY=%u,"
++ " X_method=%u, Y_method=%u",
++ mng_info->magn_mb,mng_info->magn_ml,
++ mng_info->magn_mr,mng_info->magn_mt,
++ mng_info->magn_mx,mng_info->magn_my,
++ mng_info->magn_methx,
++ mng_info->magn_methy);
++
++ /*
++ If the image width is 1, then X magnification is done
++ by simple pixel replication.
++ */
++ if (image->columns == 1)
++ mng_info->magn_methx = 1;
++
++ /*
++ If the image height is 1, then Y magnification is done
++ by simple pixel replication.
++ */
++ if (image->rows == 1)
++ mng_info->magn_methy = 1;
+
+ if (mng_info->magn_methx == 1)
+ {
+@@ -5734,12 +5757,10 @@
+ Image
+ *large_image;
+
+- int
+- yy;
+-
+ long
+ m,
+- y;
++ y,
++ yy;
+
+ register long
+ x;