Index: libexec/rtld-elf/rtld.c
===================================================================
--- libexec/rtld-elf/rtld.c
+++ libexec/rtld-elf/rtld.c
@@ -404,7 +404,16 @@
 	    i = aux_info[AT_CANARYLEN]->a_un.a_val;
 	    if (i > sizeof(__stack_chk_guard))
 		    i = sizeof(__stack_chk_guard);
-	    memcpy(__stack_chk_guard, aux_info[AT_CANARY]->a_un.a_ptr, i);
+
+	    /*
+	     * Avoid using functions which might have stack protection
+	     * enabled, to update the __stack_chk_guard.
+	     * Do a manual volatile copy to not allow the optimizer to
+	     * call memcpy() behind us.
+	     */
+	    while (--i >= 0) {
+		((char *)__stack_chk_guard)[i] = ((volatile char *)(aux_info[AT_CANARY]->a_un.a_ptr))[i];
+	    }
     } else {
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_ARND;