elf: Fix initial-exec TLS access on audit modules (BZ #28096)

For audit modules and dependencies with initial-exec TLS, we can not
set the initial TLS image on default loader initialization because it
would already be set by the audit setup.  However, subsequent thread
creation would need to follow the default behaviour.

This patch fixes it by setting l_auditing link_map field not only
for the audit modules, but also for all its dependencies.  This is
used on _dl_allocate_tls_init to avoid the static TLS initialization
at load time.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/elf/tst-audit21.c b/elf/tst-audit21.c
new file mode 100644
index 0000000..3a47ab6
--- /dev/null
+++ b/elf/tst-audit21.c
@@ -0,0 +1,42 @@
+/* Check LD_AUDIT with static TLS.
+   Copyright (C) 2022 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 <ctype.h>
+#include <support/xthread.h>
+#include <support/check.h>
+
+static volatile __thread int out __attribute__ ((tls_model ("initial-exec")));
+
+static void *
+tf (void *arg)
+{
+  TEST_COMPARE (out, 0);
+  out = isspace (' ');
+  return NULL;
+}
+
+int main (int argc, char *argv[])
+{
+  TEST_COMPARE (out, 0);
+  out = isspace (' ');
+
+  pthread_t t = xpthread_create (NULL, tf, NULL);
+  xpthread_join (t);
+
+  return 0;
+}