gdb/python: Fix segfault when iterating over empty linetable
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Commit Message
symtab-> linetable () is set to null in
buildsym_compunit::end_symtab_with_blockvector () if the symtab has no
linetable. Attempting to iterate over this linetable using the Python
API caused GDB to segfault.
---
gdb/python/py-linetable.c | 3 +-
gdb/testsuite/gdb.python/py-linetable-empty.c | 23 ++++++
.../gdb.python/py-linetable-empty.exp | 72 +++++++++++++++++++
3 files changed, 97 insertions(+), 1 deletion(-)
create mode 100644 gdb/testsuite/gdb.python/py-linetable-empty.c
create mode 100644 gdb/testsuite/gdb.python/py-linetable-empty.exp
Comments
>>>>> "Toby" == Toby Lloyd Davies <tlloyddavies@undo.io> writes:
Toby> symtab->linetable () is set to null in
Toby> buildsym_compunit::end_symtab_with_blockvector () if the symtab has no
Toby> linetable. Attempting to iterate over this linetable using the Python
Toby> API caused GDB to segfault.
Thank you for the patch. This is ok.
Approved-By: Tom Tromey <tom@tromey.com>
Tom
Thanks for the quick review.
Do I need to get a copyright assignment?
On Thu, 11 Jan 2024 at 21:14, Tom Tromey <tom@tromey.com> wrote:
>
> >>>>> "Toby" == Toby Lloyd Davies <tlloyddavies@undo.io> writes:
>
> Toby> symtab->linetable () is set to null in
> Toby> buildsym_compunit::end_symtab_with_blockvector () if the symtab has no
> Toby> linetable. Attempting to iterate over this linetable using the Python
> Toby> API caused GDB to segfault.
>
> Thank you for the patch. This is ok.
>
> Approved-By: Tom Tromey <tom@tromey.com>
>
> Tom
>>>>> "Toby" == Toby Lloyd Davies <tlloyddavies@undo.io> writes:
Toby> Thanks for the quick review.
Toby> Do I need to get a copyright assignment?
It depends. If your company has a blanket assignment, then no.
If not, then I think this is over the line limit and the answer is yes.
Tom
I don't think we have a blanket assignment. What do I need to do?
Thanks,
Toby
On Fri, 12 Jan 2024 at 15:57, Tom Tromey <tom@tromey.com> wrote:
>
> >>>>> "Toby" == Toby Lloyd Davies <tlloyddavies@undo.io> writes:
>
> Toby> Thanks for the quick review.
> Toby> Do I need to get a copyright assignment?
>
> It depends. If your company has a blanket assignment, then no.
> If not, then I think this is over the line limit and the answer is yes.
>
> Tom
@@ -397,7 +397,8 @@ ltpy_iternext (PyObject *self)
LTPY_REQUIRE_VALID (iter_obj->source, symtab);
- if (iter_obj->current_index >= symtab->linetable ()->nitems)
+ if (symtab->linetable () == nullptr
+ || iter_obj->current_index >= symtab->linetable ()->nitems)
{
PyErr_SetNone (PyExc_StopIteration);
return NULL;
new file mode 100644
@@ -0,0 +1,23 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2024 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
+main()
+{
+ asm ("main_label: .globl main_label");
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,72 @@
+# Copyright (C) 2024 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 accessing an empty linetable in Python.
+
+load_lib dwarf.exp
+load_lib gdb-python.exp
+
+require dwarf2_support allow_python_tests
+
+standard_testfile .c -dw.S
+
+set asm_file [standard_output_file ${srcfile2}]
+Dwarf::assemble $asm_file {
+
+ cu {} {
+ compile_unit {
+ {language @DW_LANG_C}
+ {name py-linetable-empty.c}
+ } {
+ subprogram {
+ {MACRO_AT_func {main}}
+ }
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+gdb_test "python print(gdb.selected_frame().function().symtab.fullname())" \
+ "py-linetable-empty.c" "Test main has symtab"
+
+# Get the linetable for main's symbol table. This is empty as we didn't include
+# a linetable in the debug info.
+gdb_py_test_silent_cmd "python lt = gdb.selected_frame().function().symtab.linetable()" \
+ "get linetable" 0
+
+gdb_test "python print(lt.is_valid())" "True" \
+ "Test linetable is valid"
+
+gdb_test "python print(lt.line(1))" "None" \
+ "Test line() returns None"
+
+gdb_test "python print(lt.has_line(1))" \
+ ".*RuntimeError: Linetable information not found in symbol table.*" \
+ "Test has_line() throws exception"
+
+gdb_test "python print(lt.source_lines())" \
+ ".*RuntimeError: Linetable information not found in symbol table.*" \
+ "Test source_lines() throws exception"
+
+gdb_test "python print(list(lt))" "\\\[\\\]" \
+ "Test iterating over linetable"