[PATCH] Fix PR server/15959

Yao Qi
2013-09-17T04:14:11Z

When I start gdbserver with option --wrapper, it hangs there. After
some analysis, it is caused by accessing two fields of
'struct thread_resume' which are uninitialized. In server.c:start_inferior,

struct thread_resume resume_info;

resume_info.thread = pid_to_ptid (signal_pid);
resume_info.kind = resume_continue;
resume_info.sig = 0;

fields 'step_range_start' and 'step_range_end' are not initialized, but
they are used in linux-low.c:lwp_in_step_range. This patch is to fix
it by set zero to 'resume_info'.

I find we don't have a test case for option '--wrapper', so I add one.
Even without the fix to server.c, gdb.server/wrapper.exp can pass on
my machine, because the uninitialized contents on stack are
undetermined.

However, fire gdbserver with 'valgrind --track-origins=yes' can report
this problem as:

==13596== Uninitialised value was created by a stack allocation
==13596== at 0x8050D88: start_inferior (server.c:203)

with this patch applied, this message goes away.

gdb/gdbserver:

2013-09-17 Yao Qi <yao@codesourcery.com>

PR server/15959
* server.c (start_inferior): Clear 'resume_info'.

gdb/testsuite/

2013-09-17 Yao Qi <yao@codesourcery.com>

* gdb.server/wrapper.c: New.
* gdb.server/wrapper.exp: New.
---
gdb/gdbserver/server.c | 1 +
gdb/testsuite/gdb.server/wrapper.c | 35 ++++++++++++++++++++++++
gdb/testsuite/gdb.server/wrapper.exp | 48 ++++++++++++++++++++++++++++++++++
3 files changed, 84 insertions(+), 0 deletions(-)
create mode 100644 gdb/testsuite/gdb.server/wrapper.c
create mode 100644 gdb/testsuite/gdb.server/wrapper.exp

diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index f4e1525..4de20d5 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -256,6 +256,7 @@ start_inferior (char **argv)
{
struct thread_resume resume_info;

+ memset (&resume_info, 0, sizeof (resume_info));
resume_info.thread = pid_to_ptid (signal_pid);
resume_info.kind = resume_continue;
resume_info.sig = 0;
diff --git a/gdb/testsuite/gdb.server/wrapper.c b/gdb/testsuite/gdb.server/wrapper.c
new file mode 100644
index 0000000..75e8c1d
--- /dev/null
+++ b/gdb/testsuite/gdb.server/wrapper.c
@@ -0,0 +1,35 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2013 Free Software Foundation, Inc.
+
+ 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/>. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static char *d = NULL;
+
+static void
+marker (void)
+{}
+
+int
+main(void)
+{
+ d = getenv("TEST");
+
+ marker ();
+
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.server/wrapper.exp b/gdb/testsuite/gdb.server/wrapper.exp
new file mode 100644
index 0000000..ee2e430
--- /dev/null
+++ b/gdb/testsuite/gdb.server/wrapper.exp
@@ -0,0 +1,48 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2013 Free Software Foundation, Inc.
+
+# 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 --wrapper option of GDBserver.
+
+load_lib gdbserver-support.exp
+
+standard_testfile
+
+if { [skip_gdbserver_tests] } {
+ return 0
+}
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile debug]} {
+ return -1
+}
+
+# Make sure we're disconnected, in case we're testing with an
+# extended-remote board, therefore already connected.
+gdb_test "disconnect" ".*"
+
+set target_exec [gdbserver_download_current_prog]
+# Start GDBserver with option '--wrapper'.
+set res [gdbserver_start "--wrapper env TEST=1 --" $target_exec]
+
+set gdbserver_protocol [lindex $res 0]
+set gdbserver_gdbport [lindex $res 1]
+gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport
+
+gdb_breakpoint marker
+gdb_test "continue" "Breakpoint.* marker .*" "continue to marker"
+# Test env var TEST is correctly passed to the program through
+# --wrapper.
+gdb_test "p d" "\\$${decimal} = ${hex} \"1\".*"
--
1.7.7.6