GraphicsMagick: coders/topol.c: Fix situation when GetBlobSize r...

changeset 1364345f71bf in /hg/GraphicsMagick
details: http://hg.GraphicsMagick.org/hg/GraphicsMagick?cmd=changeset;node=1364345f71bf
summary: coders/topol.c: Fix situation when GetBlobSize returns negative value.

diffstat:

 ChangeLog      |   4 ++++
 coders/topol.c |  11 +++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diffs (36 lines):

diff -r ffb178285bcb -r 1364345f71bf ChangeLog
--- a/ChangeLog	Fri May 05 11:26:31 2023 -0500
+++ b/ChangeLog	Sat May 06 00:03:08 2023 +0200
@@ -1,3 +1,7 @@
+2023-05-06  Fojtik Jaroslav  <[email protected]>
+
+	* coders/topol.c: Fix situation when GetBlobSize returns negative value.
+
 2023-05-05  Bob Friesenhahn  <[email protected]>
 
 	* coders/heif.c (ReadHEIFImage): Implemented Tobias Mark's idea
diff -r ffb178285bcb -r 1364345f71bf coders/topol.c
--- a/coders/topol.c	Fri May 05 11:26:31 2023 -0500
+++ b/coders/topol.c	Sat May 06 00:03:08 2023 +0200
@@ -540,14 +540,17 @@
   image->columns = Header.Cols;
   image->rows = Header.Rows;
 
-  i = GetBlobSize(image);
-  if(i>0)
-    if(((magick_uint64_t)depth*Header.Cols*(magick_uint64_t)Header.Rows) / 8 > (magick_uint64_t)GetBlobSize(image))
-      goto TOPOL_KO;    /* Check for forged image that overflows file size. */
+  j = GetBlobSize(image);
+  if(j<512)			// Header size=512bytes; negative number means failure.
+      goto TOPOL_KO;
 
   /* If ping is true, then only set image size and colors without reading any image data. */
   if (image_info->ping) goto DONE_READING;
 
+  if(j>=512)
+      if(((magick_uint64_t)depth*Header.Cols*(magick_uint64_t)Header.Rows) / 8 > (magick_uint64_t)GetBlobSize(image))
+        goto TOPOL_KO;    /* Check for forged image that overflows file size. */
+
   /* ----- Handle the reindexing mez file ----- */
   j = image->colors;
   if(j<=0 || j>256) j=256;