From: Sanimir Agovic <sanimir.agovic@intel.com>

null ptr check to prevent gdbserver from crashing

Evaluating a thread local storage variable in a remote scenario crashes
gdbserver if libthread-db could not be loaded.

2013-02-12  Sanimir Agovic  <sanimir.agovic@intel.com>

gdbserver/
	* thread-db.c (thread_db_get_tls_address):
	NULL pointer check thread_db.

testsuite/
	* gdb.server/no-thread-db.exp: New file.
	* gdb.server/no-thread-db.c: New file.
	* gdb.server/Makefile.in (EXECUTABLES): Add no-thread-db.

gdb/gdbserver/ChangeLog

@@ -1,3 +1,8 @@
+2013-02-12  Sanimir Agovic  <sanimir.agovic@intel.com>
+
+	* thread-db.c (thread_db_get_tls_address): NULL pointer check
+	thread_db.
+
 2013-02-07  Marcus Shawcroft  <marcus.shawcroft@arm.com>
 
 	* linux-aarch64-low.c (aarch64_arch_setup): Clamp

gdb/gdbserver/thread-db.c

@@ -494,7 +494,7 @@ thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
   thread_db = proc->private->thread_db;
 
   /* If the thread layer is not (yet) initialized, fail.  */
-  if (!thread_db->all_symbols_looked_up)
+  if (thread_db == NULL || !thread_db->all_symbols_looked_up)
     return TD_ERR;
 
   if (thread_db->td_thr_tls_get_addr_p == NULL)

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2013-02-12  Sanimir Agovic  <sanimir.agovic@intel.com>
+
+	* gdb.server/no-thread-db.exp: New file.
+	* gdb.server/no-thread-db.c: New file.
+	* gdb.server/Makefile.in (EXECUTABLES): Add no-thread-db.
+
 2013-02-11  Doug Evans  <dje@google.com>
 
 	* gdb.base/printcmds.exp (test_printf_with_dfp): Add test for printing

gdb/testsuite/gdb.server/Makefile.in

@@ -1,7 +1,8 @@
 VPATH = @srcdir@
 srcdir = @srcdir@
 
-EXECUTABLES = ext-attach ext-run file-transfer server-mon server-run
+EXECUTABLES = ext-attach ext-run file-transfer server-mon server-run \
+	no-thread-db
 
 MISCELLANEOUS =
 

gdb/testsuite/gdb.server/no-thread-db.c

@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012-2013 Free Software Foundation, Inc.
+
+   Contributed by Intel Corporation.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+__thread int foo;
+
+int
+main ()
+{
+  foo = 1;
+  /* after tls assignment */
+  return foo;
+}

gdb/testsuite/gdb.server/no-thread-db.exp

@@ -0,0 +1,56 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2012-2013 Free Software Foundation, Inc.
+#
+# Contributed by Intel Corporation.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test gdbserver to handle qGetTLSAddr requests gracefully in case
+# libthread_db could not be loaded.
+
+load_lib gdbserver-support.exp
+
+standard_testfile
+set unresolvable_thread_db_path "/foo/bar"
+
+if {[skip_gdbserver_tests]} {
+    return 0
+}
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    return -1
+}
+
+clean_restart ${testfile}
+
+# Make sure we're disconnected, in case we're testing with an
+# extended-remote board, therefore already connected.
+gdb_test "disconnect" ".*"
+
+gdbserver_run ""
+
+# Force gdbserver to fail to load libthread_db.
+gdb_test "monitor set libthread-db-search-path ${unresolvable_thread_db_path}" \
+    "libthread-db-search-path set to `${unresolvable_thread_db_path}'" \
+    "libthread-db is now unresolvable"
+
+# Continue past tls assignment to make sure tls storage is allocated.
+gdb_breakpoint [gdb_get_line_number "after tls assignment"]
+gdb_continue_to_breakpoint "after tls assignment"
+
+# Printing a tls variable should fail gracefully without a libthread_db.
+gdb_test "print foo" \
+    "Cannot find thread-local storage for Thread \[^,\]+, executable file ${binfile}:\[\r\n\]+Remote target failed to process qGetTLSAddr request" \
+    "print foo"