https://github.com/ImageMagick/ImageMagick/issues/1553

diff --git a/coders/xwd.c b/coders/xwd.c
index 236fbdb5ab574204f0248bec596fbbe26f9e069b..0074811a060df64305a41632b0ecca116ad2349f 100644 (file)
--- a/coders/xwd.c
+++ b/coders/xwd.c
@@ -238,6 +238,8 @@ static Image *ReadXWDImage(const ImageInfo *image_info,ExceptionInfo *exception)
     ThrowReaderException(CorruptImageError,"FileFormatVersionMismatch");
   if (header.header_size < sz_XWDheader)
     ThrowReaderException(CorruptImageError,"ImproperImageHeader");
+  if ((MagickSizeType) header.xoffset >= GetBlobSize(image))
+    ThrowReaderException(CorruptImageError,"ImproperImageHeader");
   switch (header.visual_class)
   {
     case StaticGray:
@@ -251,7 +253,7 @@ static Image *ReadXWDImage(const ImageInfo *image_info,ExceptionInfo *exception)
     case PseudoColor:
     {
       if ((header.bits_per_pixel < 1) || (header.bits_per_pixel > 15) ||
-          (header.ncolors == 0))
+          (header.colormap_entries == 0))
         ThrowReaderException(CorruptImageError,"ImproperImageHeader");
       break;
     }
@@ -318,8 +320,6 @@ static Image *ReadXWDImage(const ImageInfo *image_info,ExceptionInfo *exception)
     default:
       ThrowReaderException(CorruptImageError,"ImproperImageHeader");
   }
-  if (header.ncolors > 65535)
-    ThrowReaderException(CorruptImageError,"ImproperImageHeader");
   if (((header.bitmap_pad % 8) != 0) || (header.bitmap_pad > 32))
     ThrowReaderException(CorruptImageError,"ImproperImageHeader");
   length=(size_t) (header.header_size-sz_XWDheader);
@@ -387,8 +387,10 @@ static Image *ReadXWDImage(const ImageInfo *image_info,ExceptionInfo *exception)
       XWDColor
         color;
 
-      colors=(XColor *) AcquireQuantumMemory((size_t) header.ncolors,
-        sizeof(*colors));
+      length=(size_t) header.ncolors;
+      if (length > ((~0UL)/sizeof(*colors)))
+        ThrowReaderException(CorruptImageError,"ImproperImageHeader");
+      colors=(XColor *) AcquireQuantumMemory(length,sizeof(*colors));
       if (colors == (XColor *) NULL)
         {
           ximage=(XImage *) RelinquishMagickMemory(ximage);
@@ -689,6 +691,7 @@ ModuleExport size_t RegisterXWDImage(void)
   entry->encoder=(EncodeImageHandler *) WriteXWDImage;
 #endif
   entry->magick=(IsImageFormatHandler *) IsXWD;
+  entry->flags|=CoderDecoderSeekableStreamFlag;
   entry->flags^=CoderAdjoinFlag;
   (void) RegisterMagickInfo(entry);
   return(MagickImageCoderSignature);