https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14610

diff --git a/MagickCore/xml-tree.c b/MagickCore/xml-tree.c
index 1abeeb4f0921378e66f3668c8cafb1d6200e50c2..4edfb90115594396c7c83140fde35b87513aecaa 100644 (file)
--- a/MagickCore/xml-tree.c
+++ b/MagickCore/xml-tree.c
@@ -1731,6 +1731,8 @@ static MagickBooleanType ParseInternalDoctype(XMLTreeRoot *root,char *xml,
         if ((isalpha((int) ((unsigned char) *n)) == 0) && (*n != '_'))
           break;
         xml=n+strcspn(n,XMLWhitespace);
+        if (*xml == '\0')
+          break;
         *xml=';';
         v=xml+strspn(xml+1,XMLWhitespace)+1;
         q=(*v);