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-rw-r--r--dlfcn/Makefile3
-rw-r--r--dlfcn/Versions6
-rw-r--r--dlfcn/dlerror.c305
-rw-r--r--dlfcn/dlerror.h92
-rw-r--r--dlfcn/dlfreeres.c29
-rw-r--r--dlfcn/libc_dlerror_result.c39
-rw-r--r--elf/dl-exception.c11
-rw-r--r--elf/rtld.c1
-rw-r--r--elf/tst-dlmopen-dlerror-mod.c29
-rw-r--r--elf/tst-dlmopen-dlerror.c22
-rw-r--r--include/dlfcn.h2
-rw-r--r--malloc/set-freeres.c10
-rw-r--r--malloc/thread-freeres.c2
-rw-r--r--sysdeps/generic/ldsodefs.h7
14 files changed, 329 insertions, 229 deletions
diff --git a/dlfcn/Makefile b/dlfcn/Makefile
index d51fd08c33..994a3afee6 100644
--- a/dlfcn/Makefile
+++ b/dlfcn/Makefile
@@ -22,9 +22,10 @@ include ../Makeconfig
 headers		:= bits/dlfcn.h dlfcn.h
 extra-libs	:= libdl
 libdl-routines	:= dlopen dlclose dlsym dlvsym dlerror dladdr dladdr1 dlinfo \
-		   dlmopen dlfcn dlfreeres
+		   dlmopen dlfcn
 routines	:= $(patsubst %,s%,$(filter-out dlfcn,$(libdl-routines)))
 elide-routines.os := $(routines)
+routines += libc_dlerror_result
 
 extra-libs-others := libdl
 
diff --git a/dlfcn/Versions b/dlfcn/Versions
index 1df6925a92..f07cb929aa 100644
--- a/dlfcn/Versions
+++ b/dlfcn/Versions
@@ -1,3 +1,8 @@
+libc {
+  GLIBC_PRIVATE {
+    __libc_dlerror_result;
+  }
+}
 libdl {
   GLIBC_2.0 {
     dladdr; dlclose; dlerror; dlopen; dlsym;
@@ -13,6 +18,5 @@ libdl {
   }
   GLIBC_PRIVATE {
     _dlfcn_hook;
-    __libdl_freeres;
   }
 }
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c
index 947b7c10c6..7db70a26d0 100644
--- a/dlfcn/dlerror.c
+++ b/dlfcn/dlerror.c
@@ -25,6 +25,8 @@
 #include <libc-lock.h>
 #include <ldsodefs.h>
 #include <libc-symbols.h>
+#include <assert.h>
+#include <dlerror.h>
 
 #if !defined SHARED && IS_IN (libdl)
 
@@ -36,92 +38,75 @@ dlerror (void)
 
 #else
 
-/* Type for storing results of dynamic loading actions.  */
-struct dl_action_result
-  {
-    int errcode;
-    int returned;
-    bool malloced;
-    const char *objname;
-    const char *errstring;
-  };
-static struct dl_action_result last_result;
-static struct dl_action_result *static_buf;
-
-/* This is the key for the thread specific memory.  */
-static __libc_key_t key;
-__libc_once_define (static, once);
-
-/* Destructor for the thread-specific data.  */
-static void init (void);
-static void free_key_mem (void *mem);
-
-
 char *
 __dlerror (void)
 {
-  char *buf = NULL;
-  struct dl_action_result *result;
-
 # ifdef SHARED
   if (!rtld_active ())
     return _dlfcn_hook->dlerror ();
 # endif
 
-  /* If we have not yet initialized the buffer do it now.  */
-  __libc_once (once, init);
+  struct dl_action_result *result = __libc_dlerror_result;
 
-  /* Get error string.  */
-  if (static_buf != NULL)
-    result = static_buf;
-  else
+  /* No libdl function has been called.  No error is possible.  */
+  if (result == NULL)
+    return NULL;
+
+  /* For an early malloc failure, clear the error flag and return the
+     error message.  This marks the error as delivered.  */
+  if (result == dl_action_result_malloc_failed)
     {
-      /* init () has been run and we don't use the static buffer.
-	 So we have a valid key.  */
-      result = (struct dl_action_result *) __libc_getspecific (key);
-      if (result == NULL)
-	result = &last_result;
+      __libc_dlerror_result = NULL;
+      return (char *) "out of memory";
     }
 
-  /* Test whether we already returned the string.  */
-  if (result->returned != 0)
+  /* Placeholder object.  This can be observed in a recursive call,
+     e.g. from an ELF constructor.  */
+  if (result->errstring == NULL)
+    return NULL;
+
+  /* If we have already reported the error, we can free the result and
+     return NULL.  See __libc_dlerror_result_free.  */
+  if (result->returned)
     {
-      /* We can now free the string.  */
-      if (result->errstring != NULL)
-	{
-	  if (strcmp (result->errstring, "out of memory") != 0)
-	    free ((char *) result->errstring);
-	  result->errstring = NULL;
-	}
+      __libc_dlerror_result = NULL;
+      dl_action_result_errstring_free (result);
+      free (result);
+      return NULL;
     }
-  else if (result->errstring != NULL)
-    {
-      buf = (char *) result->errstring;
-      int n;
-      if (result->errcode == 0)
-	n = __asprintf (&buf, "%s%s%s",
-			result->objname,
-			result->objname[0] == '\0' ? "" : ": ",
-			_(result->errstring));
-      else
-	n = __asprintf (&buf, "%s%s%s: %s",
-			result->objname,
-			result->objname[0] == '\0' ? "" : ": ",
-			_(result->errstring),
-			strerror (result->errcode));
-      if (n != -1)
-	{
-	  /* We don't need the error string anymore.  */
-	  if (strcmp (result->errstring, "out of memory") != 0)
-	    free ((char *) result->errstring);
-	  result->errstring = buf;
-	}
 
-      /* Mark the error as returned.  */
-      result->returned = 1;
-    }
+  assert (result->errstring != NULL);
+
+  /* Create the combined error message.  */
+  char *buf;
+  int n;
+  if (result->errcode == 0)
+    n = __asprintf (&buf, "%s%s%s",
+		    result->objname,
+		    result->objname[0] == '\0' ? "" : ": ",
+		    _(result->errstring));
+  else
+    n = __asprintf (&buf, "%s%s%s: %s",
+		    result->objname,
+		    result->objname[0] == '\0' ? "" : ": ",
+		    _(result->errstring),
+		    strerror (result->errcode));
 
-  return buf;
+  /* Mark the error as delivered.  */
+  result->returned = true;
+
+  if (n >= 0)
+    {
+      /* Replace the error string with the newly allocated one.  */
+      dl_action_result_errstring_free (result);
+      result->errstring = buf;
+      result->errstring_source = dl_action_result_errstring_local;
+      return buf;
+    }
+  else
+    /* We could not create the combined error message, so use the
+       existing string as a fallback.  */
+    return result->errstring;
 }
 # ifdef SHARED
 strong_alias (__dlerror, dlerror)
@@ -130,130 +115,94 @@ strong_alias (__dlerror, dlerror)
 int
 _dlerror_run (void (*operate) (void *), void *args)
 {
-  struct dl_action_result *result;
-
-  /* If we have not yet initialized the buffer do it now.  */
-  __libc_once (once, init);
-
-  /* Get error string and number.  */
-  if (static_buf != NULL)
-    result = static_buf;
-  else
+  struct dl_action_result *result = __libc_dlerror_result;
+  if (result != NULL)
     {
-      /* We don't use the static buffer and so we have a key.  Use it
-	 to get the thread-specific buffer.  */
-      result = __libc_getspecific (key);
-      if (result == NULL)
+      if (result == dl_action_result_malloc_failed)
 	{
-	  result = (struct dl_action_result *) calloc (1, sizeof (*result));
-	  if (result == NULL)
-	    /* We are out of memory.  Since this is no really critical
-	       situation we carry on by using the global variable.
-	       This might lead to conflicts between the threads but
-	       they soon all will have memory problems.  */
-	    result = &last_result;
-	  else
-	    /* Set the tsd.  */
-	    __libc_setspecific (key, result);
+	  /* Clear the previous error.  */
+	  __libc_dlerror_result = NULL;
+	  result = NULL;
+	}
+      else
+	{
+	  /* There is an existing object.  Free its error string, but
+	     keep the object.  */
+	  dl_action_result_errstring_free (result);
+	  /* Mark the object as not containing an error.  This ensures
+	     that call to dlerror from, for example, an ELF
+	     constructor will not notice this result object.  */
+	  result->errstring = NULL;
 	}
     }
 
-  if (result->errstring != NULL)
-    {
-      /* Free the error string from the last failed command.  This can
-	 happen if `dlerror' was not run after an error was found.  */
-      if (result->malloced)
-	free ((char *) result->errstring);
-      result->errstring = NULL;
-    }
-
-  result->errcode = GLRO (dl_catch_error) (&result->objname,
-					   &result->errstring,
-					   &result->malloced,
-					   operate, args);
-
-  /* If no error we mark that no error string is available.  */
-  result->returned = result->errstring == NULL;
+  const char *objname;
+  const char *errstring;
+  bool malloced;
+  int errcode = GLRO (dl_catch_error) (&objname, &errstring, &malloced,
+				       operate, args);
 
-  return result->errstring != NULL;
-}
+  /* ELF constructors or destructors may have indirectly altered the
+     value of __libc_dlerror_result, therefore reload it.  */
+  result = __libc_dlerror_result;
 
-
-/* Initialize buffers for results.  */
-static void
-init (void)
-{
-  if (__libc_key_create (&key, free_key_mem))
-    /* Creating the key failed.  This means something really went
-       wrong.  In any case use a static buffer which is better than
-       nothing.  */
-    static_buf = &last_result;
-}
-
-
-static void
-check_free (struct dl_action_result *rec)
-{
-  if (rec->errstring != NULL
-      && strcmp (rec->errstring, "out of memory") != 0)
+  if (errstring == NULL)
     {
-      /* We can free the string only if the allocation happened in the
-	 C library used by the dynamic linker.  This means, it is
-	 always the C library in the base namespace.  When we're statically
-         linked, the dynamic linker is part of the program and so always
-	 uses the same C library we use here.  */
-#ifdef SHARED
-      struct link_map *map = NULL;
-      Dl_info info;
-      if (_dl_addr (check_free, &info, &map, NULL) != 0 && map->l_ns == 0)
-#endif
+      /* There is no error.  We no longer need the result object if it
+	 does not contain an error.  However, a recursive call may
+	 have added an error even if this call did not cause it.  Keep
+	 the other error.  */
+      if (result != NULL && result->errstring == NULL)
 	{
-	  free ((char *) rec->errstring);
-	  rec->errstring = NULL;
+	  __libc_dlerror_result = NULL;
+	  free (result);
 	}
+      return 0;
     }
-}
-
-
-static void
-__attribute__ ((destructor))
-fini (void)
-{
-  check_free (&last_result);
-}
-
-
-/* Free the thread specific data, this is done if a thread terminates.  */
-static void
-free_key_mem (void *mem)
-{
-  check_free ((struct dl_action_result *) mem);
+  else
+    {
+      /* A new error occurred.  Check if a result object has to be
+	 allocated.  */
+      if (result == NULL || result == dl_action_result_malloc_failed)
+	{
+	  /* Allocating storage for the error message after the fact
+	     is not ideal.  But this avoids an infinite recursion in
+	     case malloc itself calls libdl functions (without
+	     triggering errors).  */
+	  result = malloc (sizeof (*result));
+	  if (result == NULL)
+	    {
+	      /* Assume that the dlfcn failure was due to a malloc
+		 failure, too.  */
+	      if (malloced)
+		dl_error_free ((char *) errstring);
+	      __libc_dlerror_result = dl_action_result_malloc_failed;
+	      return 1;
+	    }
+	  __libc_dlerror_result = result;
+	}
+      else
+	/* Deallocate the existing error message from a recursive
+	   call, but reuse the result object.  */
+	dl_action_result_errstring_free (result);
+
+      result->errcode = errcode;
+      result->objname = objname;
+      result->errstring = (char *) errstring;
+      result->returned = false;
+      /* In case of an error, the malloced flag indicates whether the
+	 error string is constant or not.  */
+      if (malloced)
+	result->errstring_source = dl_action_result_errstring_rtld;
+      else
+	result->errstring_source = dl_action_result_errstring_constant;
 
-  free (mem);
-  __libc_setspecific (key, NULL);
+      return 1;
+    }
 }
 
 # ifdef SHARED
 
-/* Free the dlerror-related resources.  */
-void
-__dlerror_main_freeres (void)
-{
-  /* Free the global memory if used.  */
-  check_free (&last_result);
-
-  if (__libc_once_get (once) && static_buf == NULL)
-    {
-      /* init () has been run and we don't use the static buffer.
-	 So we have a valid key.  */
-      void *mem;
-      /* Free the TSD memory if used.  */
-      mem = __libc_getspecific (key);
-      if (mem != NULL)
-	free_key_mem (mem);
-    }
-}
-
 struct dlfcn_hook *_dlfcn_hook __attribute__((nocommon));
 libdl_hidden_data_def (_dlfcn_hook)
 
diff --git a/dlfcn/dlerror.h b/dlfcn/dlerror.h
new file mode 100644
index 0000000000..cb9a9cea4c
--- /dev/null
+++ b/dlfcn/dlerror.h
@@ -0,0 +1,92 @@
+/* Memory management for dlerror messages.
+   Copyright (C) 2021 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/>.  */
+
+#ifndef _DLERROR_H
+#define _DLERROR_H
+
+#include <dlfcn.h>
+#include <ldsodefs.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Source of the errstring member in struct dl_action_result, for
+   finding the right deallocation routine.  */
+enum dl_action_result_errstring_source
+  {
+   dl_action_result_errstring_constant, /* String literal, no deallocation.  */
+   dl_action_result_errstring_rtld, /* libc in the primary namespace.  */
+   dl_action_result_errstring_local, /* libc in the current namespace.  */
+  };
+
+struct dl_action_result
+{
+  int errcode;
+  char errstring_source;
+  bool returned;
+  const char *objname;
+  char *errstring;
+};
+
+/* Used to free the errstring member of struct dl_action_result in the
+   dl_action_result_errstring_rtld case.  */
+static inline void
+dl_error_free (void *ptr)
+{
+#ifdef SHARED
+  /* In the shared case, ld.so may use a different malloc than this
+     namespace.  */
+  GLRO (dl_error_free (ptr));
+#else
+  /* Call the implementation directly.  It still has to check for
+     pointers which cannot be freed, so do not call free directly
+     here.  */
+  _dl_error_free (ptr);
+#endif
+}
+
+/* Deallocate RESULT->errstring, leaving *RESULT itself allocated.  */
+static inline void
+dl_action_result_errstring_free (struct dl_action_result *result)
+{
+  switch (result->errstring_source)
+    {
+    case dl_action_result_errstring_constant:
+      break;
+    case dl_action_result_errstring_rtld:
+      dl_error_free (result->errstring);
+      break;
+    case dl_action_result_errstring_local:
+      free (result->errstring);
+      break;
+    }
+}
+
+/* Stand-in for an error result object whose allocation failed.  No
+   precise message can be reported for this, but an error must still
+   be signaled.  */
+static struct dl_action_result *const dl_action_result_malloc_failed
+  __attribute__ ((unused)) = (struct dl_action_result *) (intptr_t) -1;
+
+/* Thread-local variable for storing dlfcn failures for subsequent
+   reporting via dlerror.  */
+extern __thread struct dl_action_result *__libc_dlerror_result
+  attribute_tls_model_ie;
+void __libc_dlerror_result_free (void) attribute_hidden;
+
+#endif /* _DLERROR_H */
diff --git a/dlfcn/dlfreeres.c b/dlfcn/dlfreeres.c
deleted file mode 100644
index 856b76416d..0000000000
--- a/dlfcn/dlfreeres.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Clean up allocated libdl memory on demand.
-   Copyright (C) 2018-2021 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 <set-hooks.h>
-#include <libc-symbols.h>
-#include <dlfcn.h>
-
-/* Free libdl.so resources.
-   Note: Caller ensures we are called only once.  */
-void
-__libdl_freeres (void)
-{
-  call_function_static_weak (__dlerror_main_freeres);
-}
diff --git a/dlfcn/libc_dlerror_result.c b/dlfcn/libc_dlerror_result.c
new file mode 100644
index 0000000000..99747186b9
--- /dev/null
+++ b/dlfcn/libc_dlerror_result.c
@@ -0,0 +1,39 @@
+/* Thread-local variable holding the dlerror result.
+   Copyright (C) 2021 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <dlerror.h>
+
+/* This pointer is either NULL, dl_action_result_malloc_failed (), or
+   has been allocated using malloc by the namespace that also contains
+   this instance of the thread-local variable.  */
+__thread struct dl_action_result *__libc_dlerror_result attribute_tls_model_ie;
+
+/* Called during thread shutdown to free resources.  */
+void
+__libc_dlerror_result_free (void)
+{
+  if (__libc_dlerror_result != NULL)
+    {
+      if (__libc_dlerror_result != dl_action_result_malloc_failed)
+        {
+          dl_action_result_errstring_free (__libc_dlerror_result);
+          free (__libc_dlerror_result);
+        }
+      __libc_dlerror_result = NULL;
+    }
+}
diff --git a/elf/dl-exception.c b/elf/dl-exception.c
index 30adb7d1dc..8eaad418cb 100644
--- a/elf/dl-exception.c
+++ b/elf/dl-exception.c
@@ -30,6 +30,17 @@
    a pointer comparison.  See below and in dlfcn/dlerror.c.  */
 static const char _dl_out_of_memory[] = "out of memory";
 
+/* Call free in the main libc.so.  This allows other namespaces to
+   free pointers on the main libc heap, via GLRO (dl_error_free).  It
+   also avoids calling free on the special, pre-allocated
+   out-of-memory error message.  */
+void
+_dl_error_free (void *ptr)
+{
+  if (ptr != _dl_out_of_memory)
+    free (ptr);
+}
+
 /* Dummy allocation object used if allocating the message buffer
    fails.  */
 static void
diff --git a/elf/rtld.c b/elf/rtld.c
index fd02438936..c2ca4b7ce3 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -369,6 +369,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_open = _dl_open,
     ._dl_close = _dl_close,
     ._dl_catch_error = _rtld_catch_error,
+    ._dl_error_free = _dl_error_free,
     ._dl_tls_get_addr_soft = _dl_tls_get_addr_soft,
 #ifdef HAVE_DL_DISCOVER_OSVERSION
     ._dl_discover_osversion = _dl_discover_osversion
diff --git a/elf/tst-dlmopen-dlerror-mod.c b/elf/tst-dlmopen-dlerror-mod.c
index 7e95dcdeac..051025d3fa 100644
--- a/elf/tst-dlmopen-dlerror-mod.c
+++ b/elf/tst-dlmopen-dlerror-mod.c
@@ -18,6 +18,8 @@
 
 #include <dlfcn.h>
 #include <stddef.h>
+#include <stdio.h>
+#include <string.h>
 #include <support/check.h>
 
 /* Note: This object is not linked into the main program, so we cannot
@@ -25,17 +27,32 @@
    to use FAIL_EXIT1 (or something else that calls exit).  */
 
 void
-call_dlsym (void)
+call_dlsym (const char *name)
 {
-  void *ptr = dlsym (NULL, "does not exist");
+  void *ptr = dlsym (NULL, name);
   if (ptr != NULL)
-    FAIL_EXIT1 ("dlsym did not fail as expected");
+    FAIL_EXIT1 ("dlsym did not fail as expected for: %s", name);
+  const char *message = dlerror ();
+  if (strstr (message, ": undefined symbol: does not exist X") == NULL)
+    FAIL_EXIT1 ("invalid dlsym error message for [[%s]]: %s", name, message);
+  message = dlerror ();
+  if (message != NULL)
+    FAIL_EXIT1 ("second dlsym for [[%s]]: %s", name, message);
 }
 
 void
-call_dlopen (void)
+call_dlopen (const char *name)
 {
-  void *handle = dlopen ("tst-dlmopen-dlerror does not exist", RTLD_NOW);
+  void *handle = dlopen (name, RTLD_NOW);
   if (handle != NULL)
-    FAIL_EXIT1 ("dlopen did not fail as expected");
+    FAIL_EXIT1 ("dlopen did not fail as expected for: %s", name);
+  const char *message = dlerror ();
+  if (strstr (message, "X: cannot open shared object file:"
+              " No such file or directory") == NULL
+      && strstr (message, "X: cannot open shared object file:"
+                 " File name too long") == NULL)
+    FAIL_EXIT1 ("invalid dlopen error message for [[%s]]: %s", name, message);
+  message = dlerror ();
+  if (message != NULL)
+    FAIL_EXIT1 ("second dlopen for [[%s]]: %s", name, message);
 }
diff --git a/elf/tst-dlmopen-dlerror.c b/elf/tst-dlmopen-dlerror.c
index e864d2fe4c..aa3d6598df 100644
--- a/elf/tst-dlmopen-dlerror.c
+++ b/elf/tst-dlmopen-dlerror.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <stddef.h>
+#include <string.h>
 #include <support/check.h>
 #include <support/xdlfcn.h>
 
@@ -25,11 +26,22 @@ do_test (void)
 {
   void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-dlerror-mod.so",
                            RTLD_NOW);
-  void (*call_dlsym) (void) = xdlsym (handle, "call_dlsym");
-  void (*call_dlopen) (void) = xdlsym (handle, "call_dlopen");
-
-  call_dlsym ();
-  call_dlopen ();
+  void (*call_dlsym) (const char *name) = xdlsym (handle, "call_dlsym");
+  void (*call_dlopen) (const char *name) = xdlsym (handle, "call_dlopen");
+
+  /* Iterate over various name lengths.  This changes the size of
+     error messages allocated by ld.so and has been shown to trigger
+     detectable heap corruption if malloc/free calls in different
+     namespaces are mixed.  */
+  char buffer[2048];
+  char *buffer_end = &buffer[sizeof (buffer) - 2];
+  for (char *p = stpcpy (buffer, "does not exist "); p < buffer_end; ++p)
+    {
+      p[0] = 'X';
+      p[1] = '\0';
+      call_dlsym (buffer);
+      call_dlopen (buffer);
+    }
 
   return 0;
 }
diff --git a/include/dlfcn.h b/include/dlfcn.h
index a1816e4991..a8d48bdada 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -156,7 +156,5 @@ extern void __libc_register_dlfcn_hook (struct link_map *map)
      attribute_hidden;
 #endif
 
-extern void __dlerror_main_freeres (void) attribute_hidden;
-
 #endif
 #endif
diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
index 817fbea8b8..d404250151 100644
--- a/malloc/set-freeres.c
+++ b/malloc/set-freeres.c
@@ -20,6 +20,7 @@
 #include <set-hooks.h>
 #include <libc-internal.h>
 #include <unwind-link.h>
+#include <dlfcn/dlerror.h>
 
 #include "../nss/nsswitch.h"
 #include "../libio/libioP.h"
@@ -28,8 +29,6 @@ DEFINE_HOOK (__libc_subfreeres, (void));
 
 symbol_set_define (__libc_freeres_ptrs);
 
-extern __attribute__ ((weak)) void __libdl_freeres (void);
-
 extern __attribute__ ((weak)) void __libpthread_freeres (void);
 
 void __libc_freeres_fn_section
@@ -52,11 +51,6 @@ __libc_freeres (void)
       /* We run the resource freeing after IO cleanup.  */
       RUN_HOOK (__libc_subfreeres, ());
 
-      /* Call the libdl list of cleanup functions
-	 (weak-ref-and-check).  */
-      if (&__libdl_freeres != NULL)
-	__libdl_freeres ();
-
       /* Call the libpthread list of cleanup functions
 	 (weak-ref-and-check).  */
       if (&__libpthread_freeres != NULL)
@@ -66,6 +60,8 @@ __libc_freeres (void)
       __libc_unwind_link_freeres ();
 #endif
 
+      call_function_static_weak (__libc_dlerror_result_free);
+
       for (p = symbol_set_first_element (__libc_freeres_ptrs);
            !symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
         free (*p);
diff --git a/malloc/thread-freeres.c b/malloc/thread-freeres.c
index da76a3dca7..77a204f9fa 100644
--- a/malloc/thread-freeres.c
+++ b/malloc/thread-freeres.c
@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <dlfcn/dlerror.h>
 #include <libc-internal.h>
 #include <malloc-internal.h>
 #include <resolv/resolv-internal.h>
@@ -36,6 +37,7 @@ __libc_thread_freeres (void)
 #endif
   call_function_static_weak (__res_thread_freeres);
   __glibc_tls_internal_free ();
+  call_function_static_weak (__libc_dlerror_result_free);
 
   /* This should come last because it shuts down malloc for this
      thread and the other shutdown functions might well call free.  */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index b207f229c3..dfc117a445 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -668,6 +668,9 @@ struct rtld_global_ro
   int (*_dl_catch_error) (const char **objname, const char **errstring,
 			  bool *mallocedp, void (*operate) (void *),
 			  void *args);
+  /* libdl in a secondary namespace must use free from the base
+     namespace.  */
+  void (*_dl_error_free) (void *);
   void *(*_dl_tls_get_addr_soft) (struct link_map *);
 #ifdef HAVE_DL_DISCOVER_OSVERSION
   int (*_dl_discover_osversion) (void);
@@ -823,6 +826,10 @@ void _dl_exception_create (struct dl_exception *, const char *object,
   __attribute__ ((nonnull (1, 3)));
 rtld_hidden_proto (_dl_exception_create)
 
+/* Used internally to implement dlerror message freeing.  See
+   include/dlfcn.h and dlfcn/dlerror.c.  */
+void _dl_error_free (void *ptr) attribute_hidden;
+
 /* Like _dl_exception_create, but create errstring from a format
    string FMT.  Currently, only "%s" and "%%" are supported as format
    directives.  */