Index: pthread_mutex.c
===================================================================
RCS file: /cvsroot/src/lib/libpthread/pthread_mutex.c,v
retrieving revision 1.70
diff -u -r1.70 pthread_mutex.c
--- pthread_mutex.c	29 Jan 2020 21:11:24 -0000	1.70
+++ pthread_mutex.c	30 Jan 2020 23:20:00 -0000
@@ -131,6 +131,9 @@
 		return __libc_mutex_init_stub(ptm, attr);
 #endif
 
+	pthread__error(EINVAL, "Invalid mutes attribute",
+	    attr == NULL || attr->ptma_magic == _PT_MUTEXATTR_MAGIC);
+
 	if (attr == NULL) {
 		type = PTHREAD_MUTEX_NORMAL;
 		proto = PTHREAD_PRIO_NONE;