diff --git a/meta-python/recipes-devtools/python/python3-twisted/CVE-2026-42304.patch b/meta-python/recipes-devtools/python/python3-twisted/CVE-2026-42304.patch new file mode 100644 index 0000000000..e43ae68977 --- /dev/null +++ b/meta-python/recipes-devtools/python/python3-twisted/CVE-2026-42304.patch @@ -0,0 +1,369 @@ +From 6a1c3399c54a874673a565601bac999ab400c666 Mon Sep 17 00:00:00 2001 +From: Adi Roiban +Date: Wed, 29 Apr 2026 16:03:39 +0100 +Subject: [PATCH] Merge commit from fork + +names: mitigate DNS compression-pointer flood (GHSA-grgv-6hw6-v9g4) + +CVE: CVE-2026-42304 +Upstream-Status: Backport [https://github.com/twisted/twisted/commit/2d196123264efb0027eecfe1b430be4a9babdbd8] + +Backport Changes: +- Expanded the upstream merge and applied its complete first-parent code + and regression-test changes. +- The expanded dependency sequence is be71ecaa113f642f03083bd5ed33af47c59308c8, + 86e1b5490de5baa8ca284d1e6f4f0ade3e8ad7e0, + c75d44ed81b47f8086ed801cfcdb2568b0b32301, + d7d81e08d46b3f266963ea77e5f6b4a333af455f, + 9df6d960d3569751ebb5567093fe1d1d9f63ca54, and + 9ca319ebf61386dd33354c4ade3946ef84ad58fb. +- Retained Scarthgap's `typing.Sequence` import instead of the newer + `collections.abc.Sequence` import. +- Omitted the release-news fragment; it does not affect the fix. + +(cherry picked from commit 2d196123264efb0027eecfe1b430be4a9babdbd8) +Signed-off-by: Hetvi Thakar +--- + src/twisted/names/dns.py | 160 ++++++++++++++++++++++++++--- + src/twisted/names/test/test_dns.py | 85 +++++++++++++++ + 2 files changed, 230 insertions(+), 15 deletions(-) + +diff --git a/src/twisted/names/dns.py b/src/twisted/names/dns.py +index c7644ef50..4d093720d 100644 +--- a/src/twisted/names/dns.py ++++ b/src/twisted/names/dns.py +@@ -11,10 +11,12 @@ Future Plans: + from __future__ import annotations + + # System imports ++import contextvars + import inspect + import random + import socket + import struct ++from contextlib import contextmanager + from io import BytesIO + from itertools import chain + from typing import Optional, Sequence, SupportsInt, Union, overload +@@ -126,6 +128,7 @@ __all__ = [ + "OP_UPDATE", + "PORT", + "AuthoritativeDomainError", ++ "DNSDecodeError", + "DNSQueryTimeoutError", + "DomainError", + ] +@@ -444,6 +447,87 @@ def readPrecisely(file, l): + return buff + + ++class DNSDecodeError(ValueError): ++ """ ++ Raised when a DNS message cannot be decoded because it violates a ++ protocol-level safety limit. ++ """ ++ ++ ++class _DecodeContext: ++ """ ++ Mutable state shared between the L{IEncodable} decoders invoked while ++ reading a single DNS message. ++ ++ The primary purpose is to bound the total number of compression-pointer ++ jumps taken across every name in the message, defending against packets ++ that fan out thousands of records pointing to deeply chained pointers. ++ ++ This class is private. External callers must not rely on it; the ++ per-message scope is installed and torn down by L{Message.decode} ++ through L{_decodeContextVar}. ++ ++ @ivar jumps: The number of compression pointers followed so far. ++ @ivar maxJumps: The inclusive upper bound on L{jumps}. Exceeding it ++ causes L{registerJump} to raise L{DNSDecodeError}. ++ """ ++ ++ __slots__ = ("jumps", "maxJumps") ++ ++ def __init__(self, maxJumps: int = 1000) -> None: ++ self.jumps = 0 ++ self.maxJumps = maxJumps ++ ++ def registerJump(self) -> None: ++ """ ++ Record that a compression pointer has been followed. ++ ++ The check is performed before any further bytes are read so the ++ caller fails fast as soon as the aggregate limit is breached, even ++ if additional records remain in the buffer. ++ ++ @raise DNSDecodeError: if the cumulative number of jumps exceeds ++ L{maxJumps}. ++ """ ++ self.jumps += 1 ++ if self.jumps > self.maxJumps: ++ raise DNSDecodeError( ++ "Too many compression pointers while decoding DNS message " ++ f"(limit is {self.maxJumps})" ++ ) ++ ++ ++# Private module-level L{contextvars.ContextVar} used to share a single ++# L{_DecodeContext} across the re-entrant calls performed while decoding one ++# DNS message. L{contextvars} (rather than a plain module attribute) is used ++# on purpose: although Twisted's reactor is single-threaded, message decoding ++# is re-entrant across many records in a single pass and L{ContextVar} ++# guarantees the scope is restored correctly on exit -- and remains isolated ++# per-task should a future caller decode messages from multiple ++# L{asyncio}-style contexts concurrently. ++_decodeContextVar: contextvars.ContextVar[_DecodeContext | None] = ( ++ contextvars.ContextVar("_dnsDecodeContext", default=None) ++) ++ ++ ++@contextmanager ++def _installDecodeContext(context: _DecodeContext): ++ """ ++ Install C{context} on L{_decodeContextVar} for the duration of the ++ C{with} block and restore the previous value on exit. ++ ++ This wraps the L{contextvars.ContextVar.set} / L{contextvars.ContextVar.reset} ++ token dance so call sites can use a plain C{with} statement. ++ ++ @param context: The L{_DecodeContext} to install as the active context. ++ """ ++ token = _decodeContextVar.set(context) ++ try: ++ yield context ++ finally: ++ _decodeContextVar.reset(token) ++ ++ + class IEncodable(Interface): + """ + Interface for something which can be encoded to and decoded +@@ -549,8 +633,17 @@ class Name: + + @ivar name: A byte string giving the name. + @type name: L{bytes} ++ ++ @ivar maxCompressionPointers: Per-message cap on the total number of ++ compression-pointer dereferences L{decode} will follow before ++ raising L{DNSDecodeError}. Defaults to C{1000}. Override it on ++ a subclass or individual instance to tune the trade-off between ++ tolerance for legitimately verbose messages and resistance to ++ denial-of-service attacks. + """ + ++ maxCompressionPointers: int = 1000 ++ + def __init__(self, name: bytes | str = b""): + """ + @param name: A name. +@@ -595,16 +688,33 @@ class Name: + """ + Decode a byte string into this Name. + ++ When invoked from L{Message.decode}, a shared compression-pointer ++ counter is picked up transparently from the private ++ L{_decodeContextVar}. Standalone callers get a fresh per-call ++ counter seeded from L{maxCompressionPointers}, so existing code ++ keeps working unchanged while still being protected against ++ pathological inputs. ++ + @type strio: file + @param strio: Bytes will be read from this file until the full Name +- is decoded. ++ is decoded. ++ ++ @type length: L{int} or L{None} ++ @param length: Present for compatibility with the L{IEncodable} ++ interface; ignored by this decoder. + + @raise EOFError: Raised when there are not enough bytes available +- from C{strio}. ++ from C{strio}. ++ ++ @raise ValueError: Raised when the name cannot be decoded because ++ it contains a compression loop. + +- @raise ValueError: Raised when the name cannot be decoded (for example, +- because it contains a loop). ++ @raise DNSDecodeError: Raised when the cumulative number of ++ compression-pointer jumps exceeds the configured limit. + """ ++ context = _decodeContextVar.get() ++ if context is None: ++ context = _DecodeContext(maxJumps=self.maxCompressionPointers) + visited = set() + self.name = b"" + off = 0 +@@ -616,6 +726,7 @@ class Name: + return + if (l >> 6) == 3: + new_off = (l & 63) << 8 | ord(readPrecisely(strio, 1)) ++ context.registerJump() + if new_off in visited: + raise ValueError("Compression loop in encoded name") + visited.add(new_off) +@@ -2488,8 +2599,17 @@ class Message(tputil.FancyEqMixin): + header fields. + @ivar _sectionNames: The names of attributes representing the record + sections of this message. ++ ++ @ivar maxCompressionPointers: Per-message cap on the total number of ++ compression-pointer dereferences L{decode} will follow across every ++ name in the message before raising L{DNSDecodeError}. Defaults to ++ C{1000}. Override it on a subclass or individual instance to tune ++ the trade-off between tolerance for legitimately verbose messages ++ and resistance to denial-of-service attacks. + """ + ++ maxCompressionPointers: int = 1000 ++ + compareAttributes = ( + "id", + "answer", +@@ -2704,19 +2824,29 @@ class Message(tputil.FancyEqMixin): + self.checkingDisabled = (byte4 >> 4) & 1 + self.rCode = byte4 & 0xF + +- self.queries = [] +- for i in range(nqueries): +- q = Query() +- try: +- q.decode(strio) +- except EOFError: +- return +- self.queries.append(q) ++ # A single shared counter bounds the total compression-pointer work ++ # performed across every name in this message. It is installed on ++ # the private context variable so nested record decoders pick it up ++ # without needing to thread it through each signature. ++ decodeContext = _DecodeContext(maxJumps=self.maxCompressionPointers) ++ with _installDecodeContext(decodeContext): ++ self.queries = [] ++ for i in range(nqueries): ++ q = Query() ++ try: ++ q.decode(strio) ++ except EOFError: ++ return ++ self.queries.append(q) + +- items = ((self.answers, nans), (self.authority, nns), (self.additional, nadd)) ++ items = ( ++ (self.answers, nans), ++ (self.authority, nns), ++ (self.additional, nadd), ++ ) + +- for l, n in items: +- self.parseRecords(l, n, strio) ++ for l, n in items: ++ self.parseRecords(l, n, strio) + + def parseRecords(self, list, num, strio): + for i in range(num): +diff --git a/src/twisted/names/test/test_dns.py b/src/twisted/names/test/test_dns.py +index 3b8f6e130..3be6b4546 100644 +--- a/src/twisted/names/test/test_dns.py ++++ b/src/twisted/names/test/test_dns.py +@@ -352,6 +352,54 @@ class NameTests(unittest.TestCase): + stream = BytesIO(b"\xc0\x00") + self.assertRaises(ValueError, name.decode, stream) + ++ def test_rejectTooManyCompressionPointers(self): ++ """ ++ L{Name.decode} raises L{dns.DNSDecodeError} when it would have to ++ follow more than L{Name.maxCompressionPointers} compression ++ pointers to finish decoding a name. ++ """ ++ # Four distinct pointers chained end-to-end, terminated by a zero ++ # label byte. With maxCompressionPointers of three the fourth ++ # dereference must trip the safety limit. ++ payload = b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00" ++ name = dns.Name() ++ name.maxCompressionPointers = 3 ++ self.assertRaises( ++ dns.DNSDecodeError, name.decode, BytesIO(payload) ++ ) ++ ++ def test_decodeRecoversAfterDNSDecodeError(self): ++ """ ++ After L{Name.decode} raises L{dns.DNSDecodeError}, subsequent ++ L{Name.decode} calls continue to work. No residual ++ compression-pointer counter leaks across calls, so a legitimate ++ name decoded right after a hostile one still succeeds. ++ """ ++ # First, force a DNSDecodeError by decoding a payload that ++ # exceeds the configured limit. ++ hostile = dns.Name() ++ hostile.maxCompressionPointers = 3 ++ self.assertRaises( ++ dns.DNSDecodeError, ++ hostile.decode, ++ BytesIO(b"\xc0\x02\xc0\x04\xc0\x06\xc0\x08\x00"), ++ ) ++ ++ # Then prove the process has not been poisoned: a legitimate ++ # name still decodes normally, both with a fresh instance and ++ # with the instance that just errored. ++ stream = BytesIO() ++ dns.Name(b"example.org").encode(stream) ++ ++ fresh = dns.Name() ++ stream.seek(0) ++ fresh.decode(stream) ++ self.assertEqual(fresh.name, b"example.org") ++ ++ stream.seek(0) ++ hostile.decode(stream) ++ self.assertEqual(hostile.name, b"example.org") ++ + def test_equality(self): + """ + L{Name} instances are equal as long as they have the same value for +@@ -761,6 +809,43 @@ class MessageTests(unittest.SynchronousTestCase): + """ + self.assertEqual(dns.Message().authenticData, 0) + ++ def test_rejectCompressionPointerFlood(self): ++ """ ++ L{Message.decode} installs a shared compression-pointer counter and ++ raises L{dns.DNSDecodeError} when the aggregate number of pointer ++ dereferences across every record in the message exceeds ++ L{dns.Message.maxCompressionPointers}. ++ """ ++ chainLength = 100 ++ numRecords = 8000 ++ header = struct.pack( ++ "!H2B4H", 0x1234, 0x80, 0x00, 0, numRecords, 0, 0 ++ ) ++ ++ # Long compression chain inside the RDATA of an unknown ++ # record so that subsequent records can aim pointers at it. ++ owner = b"\x04rrrr\x00" ++ chainBase = len(header) + len(owner) + 10 ++ chain = bytearray() ++ for i in range(chainLength): ++ chain += struct.pack("!H", 0xC000 | (chainBase + 2 * (i + 1))) ++ chain += b"\x04test\x00" ++ ++ firstRecord = ( ++ owner ++ + struct.pack("!HHIH", 999, 1, 0, len(chain)) ++ + bytes(chain) ++ ) ++ followupRecord = ( ++ struct.pack("!H", 0xC000 | chainBase) ++ + struct.pack("!HHIH", 1, 1, 0, 4) ++ + b"\x00\x00\x00\x00" ++ ) ++ payload = header + firstRecord + followupRecord * (numRecords - 1) ++ ++ message = dns.Message() ++ self.assertRaises(dns.DNSDecodeError, message.decode, BytesIO(payload)) ++ + def test_authenticDataOverride(self): + """ + L{dns.Message.__init__} accepts a C{authenticData} argument which diff --git a/meta-python/recipes-devtools/python/python3-twisted_24.3.0.bb b/meta-python/recipes-devtools/python/python3-twisted_24.3.0.bb index 691b80ac68..59aef8a606 100644 --- a/meta-python/recipes-devtools/python/python3-twisted_24.3.0.bb +++ b/meta-python/recipes-devtools/python/python3-twisted_24.3.0.bb @@ -9,6 +9,7 @@ LIC_FILES_CHKSUM = "file://LICENSE;md5=c1c5d2c2493b848f83864bdedd67bbf5" SRC_URI += " \ file://CVE-2024-41671.patch \ file://CVE-2024-41810.patch \ + file://CVE-2026-42304.patch \ " SRC_URI[sha256sum] = "6b38b6ece7296b5e122c9eb17da2eeab3d98a198f50ca9efd00fb03e5b4fd4ae" @@ -178,4 +179,3 @@ FILES:${PN}-pair = " \ FILES:${PN}-doc += " \ ${PYTHON_SITEPACKAGES_DIR}/twisted/python/_pydoctortemplates \ " -