Fix for wrong fnmatch patttern

* dir.c (file_s_fnmatch): ensure that pattern does not contain a
  NUL character.  https://hackerone.com/reports/449617

1 files changed, 1 insertions, 1 deletions

diff --git a/dir.c b/dir.c
index 6d1f501927..d20cf60a7f 100644
--- a/dir.c
+++ b/dir.c
@@ -3211,7 +3211,7 @@ file_s_fnmatch(int argc, VALUE *argv, VALUE obj)
     else
 	flags = 0;
 
-    StringValue(pattern);
+    StringValueCStr(pattern);
     FilePathStringValue(path);
 
     if (flags & FNM_EXTGLOB) {