From de546e403cbbac70bbe15ab2c289c01b1ce53fc9 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Tue, 29 Apr 2025 17:01:55 +0200 Subject: [gdb] Handle nullptr gdb_std{err,out} in {gdbpy,ioscm}_flush Using the trigger patch described in the previous commit, I get: ... $ gdb (gdb) error detected on stdin Fatal signal: Segmentation fault ----- Backtrace ----- 0x64c7b3 gdb_internal_backtrace_1 /data/vries/gdb/src/gdb/bt-utils.c:127 0x64c937 _Z22gdb_internal_backtracev /data/vries/gdb/src/gdb/bt-utils.c:196 0x94db83 handle_fatal_signal /data/vries/gdb/src/gdb/event-top.c:1021 0x94dd48 handle_sigsegv /data/vries/gdb/src/gdb/event-top.c:1098 0x7f372be578ff ??? 0x10b7c0a _Z9gdb_flushP7ui_file /data/vries/gdb/src/gdb/utils.c:1527 0xd4b938 gdbpy_flush /data/vries/gdb/src/gdb/python/python.c:1624 0x7f372d73b276 _PyCFunction_FastCallDict Objects/methodobject.c:231 0x7f372d73b276 _PyCFunction_FastCallKeywords Objects/methodobject.c:294 0x7f372d794a09 call_function Python/ceval.c:4851 0x7f372d78e838 _PyEval_EvalFrameDefault Python/ceval.c:3351 0x7f372d796e6e PyEval_EvalFrameEx Python/ceval.c:754 0x7f372d796e6e _PyFunction_FastCall Python/ceval.c:4933 0x7f372d796e6e _PyFunction_FastCallDict Python/ceval.c:5035 0x7f372d6fefc8 _PyObject_FastCallDict Objects/abstract.c:2310 0x7f372d6fefc8 _PyObject_Call_Prepend Objects/abstract.c:2373 0x7f372d6fe162 _PyObject_FastCallDict Objects/abstract.c:2331 0x7f372d700705 callmethod Objects/abstract.c:2583 0x7f372d700705 _PyObject_CallMethodId Objects/abstract.c:2640 0x7f372d812a41 flush_std_files Python/pylifecycle.c:699 0x7f372d81281d Py_FinalizeEx Python/pylifecycle.c:768 0xd4d49b finalize_python /data/vries/gdb/src/gdb/python/python.c:2308 0x9587eb _Z17ext_lang_shutdownv /data/vries/gdb/src/gdb/extension.c:330 0xfd98df _Z10quit_forcePii /data/vries/gdb/src/gdb/top.c:1817 0x6b3080 _Z12quit_commandPKci /data/vries/gdb/src/gdb/cli/cli-cmds.c:483 0x1056577 stdin_event_handler /data/vries/gdb/src/gdb/ui.c:131 0x1986970 handle_file_event /data/vries/gdb/src/gdbsupport/event-loop.cc:551 0x1986f4b gdb_wait_for_event /data/vries/gdb/src/gdbsupport/event-loop.cc:672 0x1985e0c _Z16gdb_do_one_eventi /data/vries/gdb/src/gdbsupport/event-loop.cc:263 0xb66f2e start_event_loop /data/vries/gdb/src/gdb/main.c:402 0xb670ba captured_command_loop /data/vries/gdb/src/gdb/main.c:466 0xb68b9b captured_main /data/vries/gdb/src/gdb/main.c:1344 0xb68c44 _Z8gdb_mainP18captured_main_args /data/vries/gdb/src/gdb/main.c:1363 0x41a3b1 main /data/vries/gdb/src/gdb/gdb.c:38 --------------------- A fatal error internal to GDB has been detected, further debugging is not possible. GDB will now terminate. This is a bug, please report it. For instructions, see: . Segmentation fault (core dumped) $ q ... Fix this in gdbpy_flush by checking for nullptr gdb_stdout/gdb_stderr (and likewise in ioscm_flush) such that we get instead: ... $ gdb (gdb) error detected on stdin $ q ... Tested on x86_64-linux. Approved-By: Simon Marchi --- gdb/python/python.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'gdb/python') diff --git a/gdb/python/python.c b/gdb/python/python.c index 7e28eb6..24cb511 100644 --- a/gdb/python/python.c +++ b/gdb/python/python.c @@ -1612,16 +1612,19 @@ gdbpy_flush (PyObject *self, PyObject *args, PyObject *kw) { case 1: { - gdb_flush (gdb_stderr); + if (gdb_stderr != nullptr) + gdb_flush (gdb_stderr); break; } case 2: { - gdb_flush (gdb_stdlog); + if (gdb_stdlog != nullptr) + gdb_flush (gdb_stdlog); break; } default: - gdb_flush (gdb_stdout); + if (gdb_stdout != nullptr) + gdb_flush (gdb_stdout); } Py_RETURN_NONE; -- cgit v1.1