875faa29e1
9fe5896a44tor: torcontrol disconnect on too many lines to avoid OOM (David Gumberg)8b68287bf9test: Make torcontrol max line length test stricter and test boundaries. (David Gumberg)ab5889796frefactor: torcontrol add connection checks to restart_with_mock (David Gumberg) Pull request description: LLM disclosure: Found with the help of Claude Opus 4.6, fix, test, description, and commit messages written by me. ------ This fixes a low-severity issue where a misbehaving Tor control daemon can cause bitcoind to OOM by sending continuation lines without sending `250 OK` or similar. This issue is not that serious because if your tor control daemon is malicious you are already in all kinds of trouble, but as a matter of robustness this should be fixed. The fix is to prevent the `TorControlConnection::m_message` buffer from growing without bound by by limiting the number of lines handled by `TorControlConnection::ProcessBuffer()` to `MAX_LINE_COUNT = 1000`. Now the most memory that can be occupied by `m_message` is on the order of `MAX_LINE_LENGTH * MAX_LINE_COUNT= 100MB` Although this is not compliant with the Tor control protocol in general, where commands like `GETINFO ns/all` will likely return thousands of lines, it is more than sufficient for handling the replies from the commands that are used by a node: <details> <summary> #### Tor control commands used by Bitcoin Core </summary> `AUTHENTICATE`: 1 line: The server responds with 250 OK on success or 515 Bad authentication if the authentication cookie is incorrect. Tor closes the connection on an authentication failure. https://spec.torproject.org/control-spec/commands.html#authenticate `GETINFO net/listener/socks`: 2 lines A quoted, space-separated list of the locations where Tor is listening... https://spec.torproject.org/control-spec/commands.html#getinfo `AUTHCHALLENGE SAFECOOKIE`: 1 line If the server accepts the command, the server reply format is: ``` "250 AUTHCHALLENGE" SP "SERVERHASH=" ServerHash SP "SERVERNONCE=" ServerNonce CRLF ``` https://spec.torproject.org/control-spec/commands.html#authenticate `PROTOCOLINFO`: 4-5 lines The server reply format is: ``` 250-PROTOCOLINFO" SP PIVERSION CRLF \*InfoLine "250 OK" CRLF InfoLine = AuthLine / VersionLine / OtherLine ``` (https://spec.torproject.org/control-spec/commands.html#protocolinfo) `ADD_ONION`: 2-3 lines for Bitcoin Core's tor control client. The server reply format is: ``` "250-ServiceID=" ServiceID CRLF ["250-PrivateKey=" KeyType ":" KeyBlob CRLF] *("250-ClientAuth=" ClientName ":" ClientBlob CRLF) "250 OK" CRLF ``` ... The server response will only include a private key if the server was requested to generate a new keypair ... If client authorization is enabled using the “BasicAuth” flag (which is v2 only), the service will not be accessible to clients without valid authorization data (configured with the “HidServAuth” option). The list of authorized clients is specified with one or more “ClientAuth” parameters. If “ClientBlob” is not specified for a client, a new credential will be randomly generated and returned." https://spec.torproject.org/control-spec/commands.html#add_onion We don't set the `BasicAuth` flag, so the response will not include any `ClientAuthLines`. </details> ## Reproduce To reproduce this issue, the following script or similar can be used as the misbehaving Tor control daemon: ```python #!/usr/bin/env python3 """ A fake Tor control service that never finishes its reply. Sends unlimited continuation lines ("250-...") without ever sending the final "250 ...". Each line accumulates in m_message.lines with no cap. Bitcoind OOMs. """ import socket import time PORT = 19191 server = socket.create_server(("127.0.0.1", PORT)) conn, _ = server.accept() conn.recv(4096) # Receive PROTOCOLINFO time_start = time.time() try: while True: conn.sendall(b"250-Ceaseless\r\n" * 10000) except (BrokenPipeError, ConnectionResetError): elapsed = time.time() - time_start print(f"Node disconnected after {elapsed:.2f}s") ``` **🟡¡This will OOM, run in a container, VM, or some sandbox with memory limits!🟡** Start a node with `-torcontrol=127.0.0.1=19191`. E.g. with systemd: ```bash systemd-run --user --scope -p MemoryMax=2G -p MemorySwapMax=0 bitcoind -regtest -torcontrol=127.0.0.1:19191 ``` ACKs for top commit: fjahr: ACK9fe5896a44danielabrozzoni: Code review ACK9fe5896a44janb84: ACK.9fe5896a44sedited: ACK9fe5896a44Tree-SHA512: ccbeba40c096e1fa3911c75c49e3a5c403712f646d77329de48017a19d1f0caa2ee4cc148b6c6473f68e55d7da04f17eb67748b5bf4dede3579b944ee5370cf5
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.