[New-bugs-announce] [issue41597] Fatal Error on SSL Transport - sslv3 alert bad record mac

Mototsugu Emori report at bugs.python.org
Thu Aug 20 03:57:45 EDT 2020

New submission from Mototsugu Emori <mototsugu.emori at jp.ricoh.com>:

When using SSL with websocket, I get an SSLError.

[2020-08-17 15:02:51,078] websockets.protocol : Error in data transfer [MainProcess - MainThread]
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 827, in transfer_data
    message = await self.read_message()
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 895, in read_message
    frame = await self.read_data_frame(max_size=self.max_size)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 971, in read_data_frame
    frame = await self.read_frame(max_size)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 1051, in read_frame
  File "/usr/local/lib/python3.7/site-packages/websockets/framing.py", line 106, in read
    data = await reader(2)
  File "/usr/local/lib/python3.7/asyncio/streams.py", line 679, in readexactly
    await self._wait_for_data('readexactly')
  File "/usr/local/lib/python3.7/asyncio/streams.py", line 473, in _wait_for_data
    await self._waiter
  File "guac_ws_client.py", line 166, in read
    await websocket.send(instruction)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 567, in send
    await self.write_frame(True, opcode, data)
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 1077, in write_frame
    await self._drain()
  File "/usr/local/lib/python3.7/site-packages/websockets/protocol.py", line 306, in _drain
    raise exc
  File "/usr/local/lib/python3.7/asyncio/sslproto.py", line 530, in data_received
    ssldata, appdata = self._sslpipe.feed_ssldata(data)
  File "/usr/local/lib/python3.7/asyncio/sslproto.py", line 202, in feed_ssldata
    chunk = self._sslobj.read(self.max_size)
  File "/usr/local/lib/python3.7/ssl.py", line 707, in read
    v = self._sslobj.read(len)
ssl.SSLError: [SSL: SSLV3_ALERT_BAD_RECORD_MAC] sslv3 alert bad record mac (_ssl.c:2488)

When data reception (SSL_read) and data transmission (SSL_write) occur at the same time, the error seems to occur.
I made a patch(ssl.py.patch) that excludes SSL_read and SSL_write.
Could you check it?

  debian 4.19.46
  Python 3.7.3
  OpenSSL 1.1.0l  10 Sep 2019

  Re: Asyncio Fatal Error on SSL Transport - IndexError Deque Index Out Of Range

assignee: christian.heimes
components: SSL
files: ssl.py.patch
keywords: patch
messages: 375690
nosy: alex, christian.heimes, dstufft, janssen, m_emori
priority: normal
severity: normal
status: open
title: Fatal Error on SSL Transport - sslv3 alert bad record mac
type: behavior
versions: Python 3.7
Added file: https://bugs.python.org/file49410/ssl.py.patch

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