dlopen: Fix issues related to NODELETE handling and relocations

The assumption behind the assert in activate_nodelete was wrong:

Inconsistency detected by ld.so: dl-open.c: 459: activate_nodelete:
Assertion `!imap->l_init_called || imap->l_type != lt_loaded' failed! (edit)

It can happen that an already-loaded object that is in the local
scope is promoted to NODELETE status, via binding to a unique
symbol.

Similarly, it is possible that such NODELETE promotion occurs to
an already-loaded object from the global scope.  This is why the
loop in activate_nodelete has to cover all objects in the namespace
of the new object.

In do_lookup_unique, it could happen that the NODELETE status of
an already-loaded object was overwritten with a pending NODELETE
status.  As a result, if dlopen fails, this could cause a loss of
the NODELETE status of the affected object, eventually resulting
in an incorrect unload.

Fixes commit f63b73814f74032c0e5d0a83300e3d864ef905e5 ("Remove all
loaded objects if dlopen fails, ignoring NODELETE [BZ #20839]").

1 files changed, 38 insertions, 0 deletions

diff --git a/elf/tst-dlopen-nodelete-reloc-mod2.c b/elf/tst-dlopen-nodelete-reloc-mod2.c
new file mode 100644
index 0000000000..81ea8e5af2
--- /dev/null
+++ b/elf/tst-dlopen-nodelete-reloc-mod2.c
@@ -0,0 +1,38 @@
+/* Test propagation of NODELETE to an already-loaded object via relocation.
+   NODELETE helper module.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+/* Defined in tst-dlopen-nodelete-reloc-mod1.so.  This dependency is
+   not expressed via DT_NEEDED, so this reference marks the other
+   object as NODELETE dynamically, during initially relocation.  */
+extern bool may_finalize_mod1;
+
+static void __attribute__ ((destructor))
+fini (void)
+{
+  if (!may_finalize_mod1)
+    {
+      puts ("error: tst-dlopen-nodelete-reloc-mod2.so destructor"
+            " called too early");
+      _exit (1);
+    }
+}