[PATCH 19/29] perf script python: Use PyBytes for attr in trace-event-python

From: Arnaldo Carvalho de Melo
Date: Fri Jan 25 2019 - 18:19:41 EST


From: Tony Jones <tonyj@xxxxxxx>

With Python3. PyUnicode_FromStringAndSize is unsafe to call on attr and will
return NULL. Use _PyBytes_FromStringAndSize (as with raw_buf).

Below is the observed behavior without the fix. Note it is first necessary
to apply the prior fix (Add trace_context extension module to sys,modules):

# ldd /usr/bin/perf | grep -i python
libpython3.6m.so.1.0 => /usr/lib64/libpython3.6m.so.1.0 (0x00007f8e1dfb2000)

# perf record -e raw_syscalls:sys_enter /bin/false
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.018 MB perf.data (21 samples) ]

# perf script -g python | cat
generated Python script: perf-script.py

# perf script -s ./perf-script.py
in trace_begin
Segmentation fault (core dumped)

Signed-off-by: Tony Jones <tonyj@xxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jaroslav Åkarvada <jskarvad@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
Cc: Seeteena Thoufeek <s1seetee@xxxxxxxxxxxxxxxxxx>
Fixes: 66dfdff03d19 ("perf tools: Add Python 3 support")
Link: http://lkml.kernel.org/r/20190124005229.16146-3-tonyj@xxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/scripting-engines/trace-event-python.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 40300d8e80a7..777c97b13905 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -733,8 +733,7 @@ static PyObject *get_perf_sample_dict(struct perf_sample *sample,
Py_FatalError("couldn't create Python dictionary");

pydict_set_item_string_decref(dict, "ev_name", _PyUnicode_FromString(perf_evsel__name(evsel)));
- pydict_set_item_string_decref(dict, "attr", _PyUnicode_FromStringAndSize(
- (const char *)&evsel->attr, sizeof(evsel->attr)));
+ pydict_set_item_string_decref(dict, "attr", _PyBytes_FromStringAndSize((const char *)&evsel->attr, sizeof(evsel->attr)));

pydict_set_item_string_decref(dict_sample, "pid",
_PyLong_FromLong(sample->pid));
--
2.20.1