From 541d86d9e7884590c655876cd40042565293d8df Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Wed, 13 Nov 2024 08:14:06 -0600
Subject: [PATCH] Fix incorrect parsing of chunk extensions with the pure
 Python parser (#9851)

---
 CHANGES/9851.bugfix.rst   |  1 +
 aiohttp/http_parser.py    |  7 ++++++
 tests/test_http_parser.py | 48 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 CHANGES/9851.bugfix.rst

diff --git a/CHANGES/9851.bugfix.rst b/CHANGES/9851.bugfix.rst
new file mode 100644
index 0000000..02541a9
--- /dev/null
+++ b/CHANGES/9851.bugfix.rst
@@ -0,0 +1 @@
+Fixed incorrect parsing of chunk extensions with the pure Python parser -- by :user:`bdraco`.
diff --git a/aiohttp/http_parser.py b/aiohttp/http_parser.py
index b182877..af42272 100644
--- a/aiohttp/http_parser.py
+++ b/aiohttp/http_parser.py
@@ -730,6 +730,13 @@ class HttpPayloadParser:
                         i = chunk.find(CHUNK_EXT, 0, pos)
                         if i >= 0:
                             size_b = chunk[:i]  # strip chunk-extensions
+                            # Verify no LF in the chunk-extension
+                            if b"\n" in (ext := chunk[i:pos]):
+                                exc = BadHttpMessage(
+                                    f"Unexpected LF in chunk-extension: {ext!r}"
+                                )
+                                set_exception(self.payload, exc)
+                                raise exc
                         else:
                             size_b = chunk[:pos]
 
diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
index 9db34dd..6e14827 100644
--- a/tests/test_http_parser.py
+++ b/tests/test_http_parser.py
@@ -10,6 +10,7 @@ from yarl import URL
 
 import aiohttp
 from aiohttp import http_exceptions, streams
+from aiohttp.base_protocol import BaseProtocol
 from aiohttp.http_parser import (
     DeflateBuffer,
     HttpPayloadParser,
@@ -758,8 +759,53 @@ def test_parse_no_length_payload(parser) -> None:
     msg, payload = parser.feed_data(text)[0][0]
     assert payload.is_eof()
 
+@pytest.mark.skipif(NO_EXTENSIONS, reason="Only tests C parser.")
+async def test_parse_chunked_payload_with_lf_in_extensions_c_parser(
+    loop: asyncio.AbstractEventLoop, protocol: BaseProtocol
+) -> None:
+    """Test the C-parser with a chunked payload that has a LF in the chunk extensions."""
+    # The C parser will raise a BadHttpMessage from feed_data
+    parser = HttpRequestParserC(
+        protocol,
+        loop,
+        2**16,
+        max_line_size=8190,
+        max_field_size=8190,
+    )
+    payload = (
+        b"GET / HTTP/1.1\r\nHost: localhost:5001\r\n"
+        b"Transfer-Encoding: chunked\r\n\r\n2;\nxx\r\n4c\r\n0\r\n\r\n"
+        b"GET /admin HTTP/1.1\r\nHost: localhost:5001\r\n"
+        b"Transfer-Encoding: chunked\r\n\r\n0\r\n\r\n"
+    )
+    with pytest.raises(http_exceptions.BadHttpMessage, match="\\\\nxx"):
+        parser.feed_data(payload)
+async def test_parse_chunked_payload_with_lf_in_extensions_py_parser(
+    loop: asyncio.AbstractEventLoop, protocol: BaseProtocol
+) -> None:
+    """Test the py-parser with a chunked payload that has a LF in the chunk extensions."""
+    # The py parser will not raise the BadHttpMessage directly, but instead
+    # it will set the exception on the StreamReader.
+    parser = HttpRequestParserPy(
+        protocol,
+        loop,
+        2**16,
+        max_line_size=8190,
+        max_field_size=8190,
+    )
+    payload = (
+        b"GET / HTTP/1.1\r\nHost: localhost:5001\r\n"
+        b"Transfer-Encoding: chunked\r\n\r\n2;\nxx\r\n4c\r\n0\r\n\r\n"
+        b"GET /admin HTTP/1.1\r\nHost: localhost:5001\r\n"
+        b"Transfer-Encoding: chunked\r\n\r\n0\r\n\r\n"
+    )
+    messages, _, _ = parser.feed_data(payload)
+    reader = messages[0][1]
+    assert isinstance(reader.exception(), http_exceptions.BadHttpMessage)
+    assert "\\nxx" in str(reader.exception())
+
 
-def test_partial_url(parser) -> None:
+def test_partial_url(parser: HttpRequestParser) -> None:
     messages, upgrade, tail = parser.feed_data(b"GET /te")
     assert len(messages) == 0
     messages, upgrade, tail = parser.feed_data(b"st HTTP/1.1\r\n\r\n")
-- 
2.43.0

