CE fix strange characters appearing at the end of file

ce/mprintf.c

@@ -3,6 +3,7 @@
 #include <liballoc.h>
 #include <printf.h>
 #include <stdarg.h>
+#include <string.h>
 #include <system.h>
 
 void putchar_ (char ch) { (void)ch; }
@@ -18,6 +19,7 @@ void mprintf (const char* fmt, ...) {
     return;
   }
 
+  memset (buf, 0, MPRINTF_BUF_MAX);
   int len = vsnprintf (buf, MPRINTF_BUF_MAX, fmt, args);
 
   va_end (args);