Fix a potential stack overflow bug with GIF images.

michaelrsweet · Dec 22, 2021 · e4a335e · e4a335e
1 parent 753c71b
commit e4a335e
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diff --git a/CHANGES.md b/CHANGES.md
@@ -2,6 +2,7 @@
 
 - BMP image support is now deprecated and will be removed in a future
   release of HTMLDOC.
+- Fixed a potential stack overflow bug with GIF images.
 - Fixed the PDF creation date (Issue #455)
 - Fixed a potential stack overflow bug with BMP images (Issue #456)
 - Fixed a compile issue when libpng was not available (Issue #458)

diff --git a/htmldoc/image.cxx b/htmldoc/image.cxx
@@ -311,7 +311,7 @@ gif_read_image(FILE       *fp,		/* I - Input file */
 
   temp = img->pixels;
 
-  while ((pixel = gif_read_lzw(fp, 0, code_size)) >= 0)
+  while ((pixel = gif_read_lzw(fp, 0, code_size)) >= 0 && pixel < 256)
   {
     temp[0] = cmap[pixel][0];