The functional test interface_usdt_net.py currently fails on master (commit 73220fc0f958f9b65f66cf0cf042af220b312fc6) on my aarch64 machine, running Ubuntu 25.04:
0$ cmake -B build -DWITH_USDT=ON
1$ cmake --build build -j12
2# ./build/test/functional/interface_usdt_net.py
32025-08-23T10:53:12.137229Z TestFramework (INFO): PRNG seed is: 2587673157417500984
42025-08-23T10:53:12.137976Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test_iem787yt
52025-08-23T10:53:12.415409Z TestFramework (INFO): hook into the net:inbound_message and net:outbound_message tracepoints
62025-08-23T10:53:13.229315Z TestFramework (INFO): connect a P2P test node to our bitcoind node
72025-08-23T10:53:13.336504Z TestFramework (INFO): check receipt and content of in- and outbound version messages
82025-08-23T10:53:13.336668Z TestFramework (INFO): check_p2p_message(): inbound P2PMessage(peer=0, addr=127.0.0.1:54608, conn_type=inbound, msg_type=version, msg_size=111)
92025-08-23T10:53:13.341459Z TestFramework (ERROR): Unexpected exception
10Traceback (most recent call last):
11 File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 195, in main
12 self.run_test()
13 ~~~~~~~~~~~~~^^
14 File "/home/thestack/bitcoin/./build/test/functional/interface_usdt_net.py", line 260, in run_test
15 self.p2p_message_tracepoint_test()
16 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
17 File "/home/thestack/bitcoin/./build/test/functional/interface_usdt_net.py", line 334, in p2p_message_tracepoint_test
18 check_p2p_message(event, is_inbound)
19 ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
20 File "/home/thestack/bitcoin/./build/test/functional/interface_usdt_net.py", line 300, in check_p2p_message
21 if event.msg_type.decode("utf-8") == "version":
22 ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
23UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa8 in position 0: invalid start byte
24.....
The message type parameter in the net:outbound_message tracepoint seems to point to garbage at the time it is evaluated in the probe, as printing out the event.msg_type contents over a few test runs shows:
0event.msg_type == b'\xa8\xc2\xffG\xff\xff'
1event.msg_type == b'\xa8\xb2\xfbt\xff\xff'
2event.msg_type == b'\xa8\xb2|i\xff\xff'
3event.msg_type == b'\xa8\xc2\xffo\xff\xff'
4event.msg_type == b'\xa8\xc2~S\xff\xff'
5.....
It looks like a potential life-time issue, but it’s unclear to me how this could be possible at all (see also e.g. #27380 (comment)), given that probes should be executed synchronously and the relevant msgtype object is clearly still alive after the tracepoint call (msg gets std::moved later in the function though):
https://github.com/bitcoin/bitcoin/blob/73220fc0f958f9b65f66cf0cf042af220b312fc6/src/net.cpp#L3885
OS / compiler / packages:
0$ head -1 /etc/issue
1Ubuntu 25.04 \n \l
2$ uname -s -r -v -m
3Linux 6.16.0-21-qcom-x1e [#21](/bitcoin-bitcoin/21/)-Ubuntu SMP PREEMPT_DYNAMIC Sun Aug 10 00:54:48 UTC 2025 aarch64
4$ gcc --version | head -1
5gcc (Ubuntu 14.2.0-19ubuntu2) 14.2.0
6$ apt info systemtap-sdt-dev | grep Version
7Version: 5.1-4.1
