[2/2] elf: Test dlopen (NULL, RTLD_LAZY) from an ELF constructor

diff --git a/elf/Makefile b/elf/Makefile
index fda796f6d5..2376789ead 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -415,6 +415,7 @@  tests += \
   tst-dlmopen3 \
   tst-dlmopen4 \
   tst-dlopen-auditdup \
+  tst-dlopen-constructor-null \
   tst-dlopen-self \
   tst-dlopen-tlsmodid \
   tst-dlopen-tlsreinit1 \
@@ -868,6 +869,8 @@  modules-names += \
   tst-dlmopen1mod \
   tst-dlopen-auditdup-auditmod \
   tst-dlopen-auditdupmod \
+  tst-dlopen-constructor-null-mod1 \
+  tst-dlopen-constructor-null-mod2 \
   tst-dlopen-tlsreinitmod1 \
   tst-dlopen-tlsreinitmod2 \
   tst-dlopen-tlsreinitmod3 \
@@ -3160,3 +3163,9 @@  tst-dlopen-tlsreinit4-ENV = LD_AUDIT=$(objpfx)tst-auditmod1.so
 tst-dlopen-auditdup-ENV = LD_AUDIT=$(objpfx)tst-dlopen-auditdup-auditmod.so
 $(objpfx)tst-dlopen-auditdup.out: \
   $(objpfx)tst-dlopen-auditdupmod.so $(objpfx)tst-dlopen-auditdup-auditmod.so
+
+$(objpfx)tst-dlopen-constructor-null: \
+  $(objpfx)tst-dlopen-constructor-null-mod1.so \
+  $(objpfx)tst-dlopen-constructor-null-mod2.so
+$(objpfx)tst-dlopen-constructor-null-mod2.so: \
+  $(objpfx)tst-dlopen-constructor-null-mod1.so
diff --git a/elf/dl-open.c b/elf/dl-open.c
index ba3c266e6a..8fdc631a1d 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -594,6 +594,16 @@  dl_open_worker_begin (void *a)
       if ((mode & RTLD_GLOBAL) && new->l_global == 0)
 	add_to_global_update (new);
 
+      /* It is not possible to run the ELF constructor for the new
+	 link map if it has not executed yet: If this dlopen call came
+	 from an ELF constructor that has not put that object into a
+	 consistent state, completing initialization for the entire
+	 scope will expose objects that have this partially
+	 constructed object among its dependencies to this
+	 inconsistent state.  This could happen even with a benign
+	 dlopen (NULL, RTLD_LAZY) call from a constructor of an
+	 initially loaded shared object.  */
+
       return;
     }
 
diff --git a/elf/tst-dlopen-constructor-null-mod1.c b/elf/tst-dlopen-constructor-null-mod1.c
new file mode 100644
index 0000000000..70a7a0ad46
--- /dev/null
+++ b/elf/tst-dlopen-constructor-null-mod1.c
@@ -0,0 +1,55 @@ 
+/* Module calling dlopen (NULL, RTLD_LAZY) to obtain the global scope.
+   Copyright (C) 2024 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 <dlfcn.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int mod1_status;
+
+static void __attribute__ ((constructor))
+init (void)
+{
+  puts ("info: tst-dlopen-constructor-null-mod1.so constructor");
+
+  void *handle = dlopen (NULL, RTLD_LAZY);
+  if (handle == NULL)
+    {
+      printf ("error: %s\n", dlerror ());
+      exit (1);
+    }
+  puts ("info: dlopen returned");
+  if (dlsym (handle, "malloc") != malloc)
+    {
+      puts ("error: dlsym did not produce expected result");
+      exit (1);
+    }
+  dlclose (handle);
+
+  /* Check that the second module's constructor has not executed.   */
+  if (getenv ("mod2_status") != NULL)
+    {
+      printf ("error: mod2_status environment variable set: %s\n",
+              getenv ("mod2_status"));
+      exit (1);
+    }
+
+  /* Communicate to the second module that the constructor executed.   */
+  mod1_status = 1;
+}
diff --git a/elf/tst-dlopen-constructor-null-mod2.c b/elf/tst-dlopen-constructor-null-mod2.c
new file mode 100644
index 0000000000..d6e945beae
--- /dev/null
+++ b/elf/tst-dlopen-constructor-null-mod2.c
@@ -0,0 +1,37 @@ 
+/* Module whose constructor should not be invoked by dlopen (NULL, RTLD_LAZY).
+   Copyright (C) 2024 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 <stdio.h>
+#include <stdlib.h>
+
+extern int mod1_status;
+int mod2_status;
+
+static void __attribute__ ((constructor))
+init (void)
+{
+  printf ("info: tst-dlopen-constructor-null-mod2.so constructor"
+          " (mod1_status=%d)", mod1_status);
+  if (!(mod1_status == 1 && mod2_status == 0))
+    {
+      puts ("error: mod1_status == 1 && mod2_status == 0 expected");
+      exit (1);
+    }
+  setenv ("mod2_status", "constructed", 1);
+  mod2_status = 1;
+}
diff --git a/elf/tst-dlopen-constructor-null.c b/elf/tst-dlopen-constructor-null.c
new file mode 100644
index 0000000000..58c4660c7d
--- /dev/null
+++ b/elf/tst-dlopen-constructor-null.c
@@ -0,0 +1,38 @@ 
+/* Verify that dlopen (NULL, RTLD_LAZY) does not complete initialization.
+   Copyright (C) 2024 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 test mimics what the glvndSetupPthreads function in libglvnd
+   does. */
+
+#include <stdlib.h>
+#include <support/check.h>
+
+/* Defined an initialized in the shared objects.  */
+extern int mod1_status;
+extern int mod2_status;
+
+static int
+do_test (void)
+{
+  TEST_COMPARE (mod1_status, 1);
+  TEST_COMPARE (mod2_status, 1);
+  TEST_COMPARE_STRING (getenv ("mod2_status"), "constructed");
+  return 0;
+}
+
+#include <support/test-driver.c>