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, 35 insertions, 0 deletions

diff --git a/elf/tst-dlopen-nodelete-reloc.h b/elf/tst-dlopen-nodelete-reloc.h
new file mode 100644
index 0000000000..8844de6226
--- /dev/null
+++ b/elf/tst-dlopen-nodelete-reloc.h
@@ -0,0 +1,35 @@
+/* Template to produce unique symbols.
+   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/>.  */
+
+/* This template produces a unique symbol definition for an explicit
+   template instantiation (without also incorporating a reference),
+   and an extern template declaration can be used to reference that
+   symbol from another object.  The modid parameter is just a
+   placeholder to create different symbols (because it affects the
+   name mangling of the static value member).  By convention, it
+   should match the number of the module that contains the
+   definition.  */
+
+template <int modid>
+struct unique_symbol
+{
+  static int value;
+};
+
+template <int modid>
+int unique_symbol<modid>::value;