[PATCH hci-8.1 0/6] io/channel-websock: fix an unauthenticated crash in the handshake #VSTOR-143316

["Denis V. Lunev" <den@openvz.org>]

Backport of the upstream series fixing an unauthenticated crash in the
VNC websocket handshake. A client which can reach a websocket port
crashes QEMU before it has authenticated, by sending an HTTP greeting
whose request line holds no space:

  printf 'stats\r\nx\r\n\r\n' | nc $host $port

Three defects line up to produce it. The greeting is rejected without
queueing a response, so the handshake goes on to flush an empty buffer.
A zero length sendmsg() succeeds and returns 0, which
qio_channel_socket_writev() mistakes for failure and reports as
QIO_CHANNEL_ERR_BLOCK with errp left unset. The handshake treats every
negative return as fatal and hands that NULL Error to
error_get_pretty(). Patches 1 to 3 close the three links.

Patch 5 is the same NULL Error on the read side of the handshake, where
ERR_BLOCK is folded into -1. It is reachable for a wss:// client, whose
master channel is then a TLS channel: a wakeup carrying only part of a
record makes gnutls report EAGAIN.

The series applies to the branch unchanged, and the new unit test passes
on it.

Upstream posting, reviewed by the graphics maintainer:
https://lore.kernel.org/qemu-devel/20260831100151.914178-1-den@openvz.org/

Signed-off-by: Denis V. Lunev <den@openvz.org>

Denis V. Lunev (6):
  io/channel-socket: do not treat a zero length write as an error
    #VSTOR-143316
  io/channel-websock: send an HTTP 400 when the greeting has no space
    #VSTOR-143316
  io/channel-websock: handle a blocked write during the handshake
    #VSTOR-143316
  tests/unit: add websock handshake test #VSTOR-143316
  io/channel-websock: do not lose QIO_CHANNEL_ERR_BLOCK while reading
    #VSTOR-143316
  tests/unit: cover blocked IO during the websock handshake
    #VSTOR-143316

 io/channel-socket.c                  |   2 +-
 io/channel-websock.c                 |  10 +-
 tests/unit/meson.build               |   1 +
 tests/unit/test-io-channel-websock.c | 249 +++++++++++++++++++++++++++
 4 files changed, 260 insertions(+), 2 deletions(-)
 create mode 100644 tests/unit/test-io-channel-websock.c

-- 
2.53.0