Commit f4952523 authored by Pierre-Marie de Rodat's avatar Pierre-Marie de Rodat
Browse files

Fix use of a dangling pointer for Python breakpoint objects

When a Python script tries to create a breakpoint but fails to do so,
gdb.Breakpoint.__init__ raises an exception and the breakpoint does not
exist anymore in the Python interpreter. However, GDB still keeps a
reference to the Python object to be used for a later hook, which is
wrong.

This commit adds the necessary cleanup code so that there is no stale
reference to this Python object. It also adds a new testcase to
reproduce the bug and check the fix.

2016-06-25  Pierre-Marie de Rodat  <derodat@adacore.com>

gdb/
	* python/py-breakpoint.c (bppy_init): Clear bppy_pending_object
	when there is an error during the breakpoint creation.

gdb/testsuite

	* gdb.python/py-breakpoint-create-fail.c,
	gdb.python/py-breakpoint-create-fail.exp,
	gdb.python/py-breakpoint-create-fail.py: New testcase.
parent 3cd72572
2016-06-25 Pierre-Marie de Rodat <derodat@adacore.com>
* python/py-breakpoint.c (bppy_init): Clear bppy_pending_object
when there is an error during the breakpoint creation.
2016-06-25 Tom Tromey <tom@tromey.com>
* rust-lang.c (rust_get_disr_info, rust_print_type): Fix
......
......@@ -705,6 +705,7 @@ bppy_init (PyObject *self, PyObject *args, PyObject *kwargs)
}
CATCH (except, RETURN_MASK_ALL)
{
bppy_pending_object = NULL;
PyErr_Format (except.reason == RETURN_QUIT
? PyExc_KeyboardInterrupt : PyExc_RuntimeError,
"%s", except.message);
......
2016-06-27 Pierre-Marie de Rodat <derodat@adacore.com>
* gdb.python/py-breakpoint-create-fail.c,
gdb.python/py-breakpoint-create-fail.exp,
gdb.python/py-breakpoint-create-fail.py: New testcase.
2016-06-25 Manish Goregaokar <manish@mozilla.com>
PR gdb/20239
......
/* This testcase is part of GDB, the GNU debugger.
Copyright 2016 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/>. */
int
foo (int a)
{
return a * 2;
}
int
main (void)
{
return foo (2);
}
# Copyright (C) 2016 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/>.
# This file is part of the GDB testsuite. It tests proper handling for
# breakpoint creation failure.
load_lib gdb-python.exp
standard_testfile
if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
return -1
}
# Skip all tests if Python scripting is not enabled.
if { [skip_python_tests] } { continue }
clean_restart "${testfile}"
if ![runto_main] {
perror "could not run to main"
continue
}
# The following will create a breakpoint Python wrapper whose construction will
# abort: the requested symbol is not defined. GDB should not keep a reference
# to the wrapper; however it used to...
gdb_test "source py-breakpoint-create-fail.py"
# ... and when it did, as a result, the following breakpoint creation (not
# initiated by the Python API) would dereference the already-freed Python
# breakpoint wrapper, resulting in undefined behavior, sometimes observed as a
# gdb crash, and other times causing the next stop to invoke the Python wrapper
# "stop" method for the object that is not supposed to exist.
gdb_test "break foo"
set test "continuing to foo"
gdb_test_multiple "continue" "$test" {
-re "MyBP\.stop was invoked\!.*$gdb_prompt $" {
fail "$test"
}
-re "Continuing.*Breakpoint 2, foo.*$gdb_prompt $" {
pass "$test"
}
}
# Copyright (C) 2016 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/>.
import gdb
class MyBP(gdb.Breakpoint):
def stop(self):
print('MyBP.stop was invoked!')
# Don't make this breakpoint stop
return False
try:
bp = MyBP('does_not_exist', gdb.BP_WATCHPOINT)
except RuntimeError:
pass
else:
assert False
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