https://github.com/ImageMagick/ImageMagick/issues/8557

Author: Cristy

coders/pwp.c

@@ -227,7 +227,7 @@ static Image *ReadPWPImage(const ImageInfo *image_info,ExceptionInfo *exception)
       }
     length=fwrite("SFW94A",1,6,file);
     (void) length;
-    filesize=65535UL*magick[2]+256L*magick[1]+magick[0];
+    filesize=65535*magick[2]+256L*magick[1]+magick[0];
     for (i=0; i < (ssize_t) filesize; i++)
     {
       c=ReadBlobByte(pwp_image);

coders/stegano.c

@@ -212,7 +212,7 @@ static Image *ReadSTEGANOImage(const ImageInfo *image_info,
         if (c == 3)
           c=0;
         k++;
-        if (k == (ssize_t) (watermark->columns*watermark->columns))
+        if (k == (ssize_t) (watermark->columns*watermark->rows))
           k=0;
         if (k == image->offset)
           j++;

coders/xpm.c

@@ -445,10 +445,12 @@ static Image *ReadXPMImage(const ImageInfo *image_info,ExceptionInfo *exception)
         else
           (void) CopyMagickString(target,q,MaxTextExtent);
         q=ParseXPMColor(target,MagickFalse);
-        (void) CopyXPMColor(symbolic,q,MagickMin((size_t) (next-q),
-          MagickPathExtent-1));
         if (q != (char *) NULL)
-          *q='\0';
+          {
+            (void) CopyXPMColor(symbolic,q,MagickMin((size_t) (next-q),
+              MagickPathExtent-1));
+            *q='\0';
+          }
       }
     StripString(target);
     if (*symbolic != '\0')