5.4-stable review patch. If anyone has any objections, please let me know.
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From: Arnaldo Carvalho de Melo acme@redhat.com
[ Upstream commit 89aaeaf84231157288035b366cb6300c1c6cac64 ]
The pyrf_event__new() method copies the event obtained from the perf ring buffer to a structure that will then be turned into a python object for further consumption, so it copies perf_event.header.size bytes to its 'event' member:
$ pahole -C pyrf_event /tmp/build/perf-tools-next/python/perf.cpython-312-x86_64-linux-gnu.so struct pyrf_event { PyObject ob_base; /* 0 16 */ struct evsel * evsel; /* 16 8 */ struct perf_sample sample; /* 24 312 */
/* XXX last struct has 7 bytes of padding, 2 holes */
/* --- cacheline 5 boundary (320 bytes) was 16 bytes ago --- */ union perf_event event; /* 336 4168 */
/* size: 4504, cachelines: 71, members: 4 */ /* member types with holes: 1, total: 2 */ /* paddings: 1, sum paddings: 7 */ /* last cacheline: 24 bytes */ };
$
It was doing so without checking if the event just obtained has more than that space, fix it.
This isn't a proper, final solution, as we need to support larger events, but for the time being we at least bounds check and document it.
Fixes: 877108e42b1b9ba6 ("perf tools: Initial python binding") Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Reviewed-by: Ian Rogers irogers@google.com Link: https://lore.kernel.org/r/20250312203141.285263-7-acme@kernel.org Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/python.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c index 594c738e4930f..3cfaa843b6a9d 100644 --- a/tools/perf/util/python.c +++ b/tools/perf/util/python.c @@ -537,6 +537,11 @@ static PyObject *pyrf_event__new(union perf_event *event) event->header.type == PERF_RECORD_SWITCH_CPU_WIDE)) return NULL;
+ // FIXME this better be dynamic or we need to parse everything + // before calling perf_mmap__consume(), including tracepoint fields. + if (sizeof(pevent->event) < event->header.size) + return NULL; + ptype = pyrf_event__type[event->header.type]; pevent = PyObject_New(struct pyrf_event, ptype); if (pevent != NULL)