va_copy is meant to be matched by a va_end in log_generic.

logging.c

@@ -105,6 +105,7 @@ static void log_generic(int prio, const char *fmt, va_list ap)
 
 			va_copy(apc, ap);
 			vfprintf(stderr, f, apc);	/* atomic write to stderr */
+			va_end(apc);
 			fflush(stderr);
 		}