https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5869

diff --git a/MagickCore/fx.c b/MagickCore/fx.c
index 954b69514e6dcd691c304f6d76bfafb69d0b1337..c62f568009a289385c97a238db77d8fd95c69774 100644 (file)
--- a/MagickCore/fx.c
+++ b/MagickCore/fx.c
@@ -1872,11 +1872,11 @@ static const char *FxOperatorPrecedence(const char *expression,
   size_t
     level;
 
-  c=0;
+  c=(-1);
   level=0;
   subexpression=(const char *) NULL;
   target=NullPrecedence;
-  while (*expression != '\0')
+  while ((c != '\0') && (*expression != '\0'))
   {
     precedence=UndefinedPrecedence;
     if ((isspace((int) ((unsigned char) *expression)) != 0) || (c == (int) '@'))