cjpeg: Fix FPE when compressing 0-width GIF

Fixes #493

ChangeLog.md

@@ -15,6 +15,10 @@ block smoothing algorithm to read from uninitialized memory.
 encoders to generate incorrect results when using the Clang compiler with
 Visual Studio.
 
+4. Fixed a floating point exception that occurred when attempting to compress a
+specially-crafted malformed GIF image with a specified image width of 0 using
+cjpeg.
+
 
 2.0.90 (2.1 beta1)
 ==================

cderror.h

@@ -1,9 +1,11 @@
 /*
  * cderror.h
  *
+ * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1994-1997, Thomas G. Lane.
  * Modified 2009-2017 by Guido Vollbeding.
- * This file is part of the Independent JPEG Group's software.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2021, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -60,6 +62,7 @@ JMESSAGE(JTRC_BMP_OS2_MAPPED, "%ux%u 8-bit colormapped OS2 BMP image")
 JMESSAGE(JERR_GIF_BUG, "GIF output got confused")
 JMESSAGE(JERR_GIF_CODESIZE, "Bogus GIF codesize %d")
 JMESSAGE(JERR_GIF_COLORSPACE, "GIF output must be grayscale or RGB")
+JMESSAGE(JERR_GIF_EMPTY, "Empty GIF image")
 JMESSAGE(JERR_GIF_IMAGENOTFOUND, "Too few images in GIF file")
 JMESSAGE(JERR_GIF_NOT, "Not a GIF file")
 JMESSAGE(JTRC_GIF, "%ux%ux%d GIF image")

rdgif.c

@@ -1,9 +1,11 @@
 /*
  * rdgif.c
  *
+ * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 2019 by Guido Vollbeding.
- * This file is part of the Independent JPEG Group's software.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2021, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -404,6 +406,8 @@ start_input_gif(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
     ERREXIT(cinfo, JERR_INPUT_EOF);
   width = LM_to_uint(hdrbuf, 0);
   height = LM_to_uint(hdrbuf, 2);
+  if (width == 0 || height == 0)
+    ERREXIT(cinfo, JERR_GIF_EMPTY);
   /* we ignore the color resolution, sort flag, and background color index */
   aspectRatio = UCH(hdrbuf[6]);
   if (aspectRatio != 0 && aspectRatio != 49)
@@ -446,6 +450,8 @@ start_input_gif(j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
     /* we ignore top/left position info, also sort flag */
     width = LM_to_uint(hdrbuf, 4);
     height = LM_to_uint(hdrbuf, 6);
+    if (width == 0 || height == 0)
+      ERREXIT(cinfo, JERR_GIF_EMPTY);
     source->is_interlaced = (BitSet(hdrbuf[8], INTERLACE) != 0);
 
     /* Read local colormap if header indicates it is present */