commit 58b90461ae100c95e0bc53d29d2187bad290ecaf
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Jun 17 15:06:43 2021 +0200

    elf: Use _dl_catch_error from base namespace in dl-libc.c [BZ #27646]
    
    dlerrror_run in elf/dl-libc.c needs to call GLRO (dl_catch_error)
    from the base namespace, just like the exported dlerror
    implementation.
    
    Fixes commit b2964eb1d9a6b8ab1250e8a881cf406182da5875 ("dlfcn:
    Failures after dlmopen should not terminate process [BZ #24772]").
    
    Backport notes: GLRO (dl_catch_error) is replaced with
    _dl_catch_error_ptr to preserve _rtld_global_ro layout.
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    (cherry picked from commit c2059edce20c124d1a99f1a94cc52e83b77a917a)

diff --git a/elf/Makefile b/elf/Makefile
index 509475dd9914e6f3..4fc3bd8239c8a99b 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -227,7 +227,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-single_threaded tst-single_threaded-pthread \
 	 tst-tls-ie tst-tls-ie-dlmopen argv0test \
 	 tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
-	 tst-dlmopen-dlerror
+	 tst-dlmopen-dlerror tst-dlmopen-gethostbyname
 #	 reldep9
 tests-internal += loadtest unload unload2 circleload1 \
 	 neededtest neededtest2 neededtest3 neededtest4 \
@@ -349,7 +349,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		libmarkermod2-1 libmarkermod2-2 \
 		libmarkermod3-1 libmarkermod3-2 libmarkermod3-3 \
 		libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
-		tst-dlmopen-dlerror-mod \
+		tst-dlmopen-dlerror-mod tst-dlmopen-gethostbyname-mod \
 
 # Most modules build with _ISOMAC defined, but those filtered out
 # depend on internal headers.
@@ -1926,3 +1926,6 @@ $(objpfx)tst-rtld-help.out: $(objpfx)ld.so
 	fi; \
 	(exit $$status); \
 	$(evaluate-test)
+
+$(objpfx)tst-dlmopen-gethostbyname: $(libdl)
+$(objpfx)tst-dlmopen-gethostbyname.out: $(objpfx)tst-dlmopen-gethostbyname-mod.so
diff --git a/elf/dl-libc.c b/elf/dl-libc.c
index ed551f6e56b3cb31..e2236d87d1df4cfa 100644
--- a/elf/dl-libc.c
+++ b/elf/dl-libc.c
@@ -43,9 +43,15 @@ dlerror_run (void (*operate) (void *), void *args)
   const char *last_errstring = NULL;
   bool malloced;
 
+#ifdef SHARED
+  int result = (_dl_catch_error_ptr (&objname, &last_errstring, &malloced,
+				     operate, args)
+		?: last_errstring != NULL);
+#else
   int result = (_dl_catch_error (&objname, &last_errstring, &malloced,
-				operate, args)
+				 operate, args)
 		?: last_errstring != NULL);
+#endif
 
   if (result && malloced)
     free ((char *) last_errstring);
diff --git a/elf/tst-dlmopen-gethostbyname-mod.c b/elf/tst-dlmopen-gethostbyname-mod.c
new file mode 100644
index 0000000000000000..9a68ea5050c3060b
--- /dev/null
+++ b/elf/tst-dlmopen-gethostbyname-mod.c
@@ -0,0 +1,29 @@
+/* Exercise dlerror_run in elf/dl-libc.c after dlmopen, via NSS.  Helper module.
+   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/>.  */
+
+#include <netdb.h>
+#include <nss.h>
+
+void
+call_gethostbyname (void)
+{
+  __nss_configure_lookup ("hosts", "files");
+  /* This should not terminate the process due to a missing
+     _nss_files_getcanonname_r symbol.  */
+  gethostbyname ("localhost");
+}
diff --git a/elf/tst-dlmopen-gethostbyname.c b/elf/tst-dlmopen-gethostbyname.c
new file mode 100644
index 0000000000000000..12deb29900731c20
--- /dev/null
+++ b/elf/tst-dlmopen-gethostbyname.c
@@ -0,0 +1,31 @@
+/* Exercise dlerror_run in elf/dl-libc.c after dlmopen, via NSS (bug 27646).
+   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/>.  */
+
+#include <support/xdlfcn.h>
+
+static int
+do_test (void)
+{
+  void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-gethostbyname-mod.so",
+                           RTLD_NOW);
+  void (*call_gethostbyname) (void) = xdlsym (handle, "call_gethostbyname");
+  call_gethostbyname ();
+  return 0;
+}
+
+#include <support/test-driver.c>