[PATCH v2 0/2] block: Use 'read-zeroes=true' mode by default with 'null-co' driver

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

The null-co driver doesn't zeroize buffer in its default config,
because it is designed for testing and tests want to run fast.
However this confuses security researchers (access to uninit
buffers).

A one-line patch supposed which became a painful one, because
there is so many different syntax to express the same usage:

 opt = qdict_new();
 qdict_put_str(opt, "read-zeroes", "off");
 null_bs = bdrv_open("null-co://", NULL, opt, BDRV_O_RDWR | BDRV_O_PROTOCOL,
                     &error_abort);

vm.qmp('blockdev-add', driver='null-co', read_zeroes=False, ...)

vm.add_drive_raw("id=drive0,driver=null-co,read-zeroes=off,if=none")

    blk0 = { 'node-name': 'src',
        'driver': 'null-co',
        'read-zeroes': 'off' }

    'file': {
        'driver': 'null-co',
        'read-zeroes': False,
    }

    "file": {
        "driver": "null-co",
        "read-zeroes": "off"
    }

    { "execute": "blockdev-add",
      "arguments": {
          "driver": "null-co",
          "read-zeroes": false,
          "node-name": "disk0"
        }
    }

opts = {'driver': 'null-co,read-zeroes=off', 'node-name': 'root', 'size': 1024}

qemu -drive driver=null-co,read-zeroes=off

qemu-io ... "json:{'driver': 'null-co', 'read-zeroes': false, 'size': 65536}"

qemu-img null-co://,read-zeroes=off

qemu-img ... -o data_file="json:{'driver':'null-co',,'read-zeroes':false,,'size':'4294967296'}"

There are probably more.

Anyhow, the iotests I am not sure and should be audited are 056, 155
(I don't understand the syntax) and 162.

Please review,

Phil.

Philippe Mathieu-Daud=C3=A9 (2):
  block: Explicit null-co uses 'read-zeroes=3Dfalse'
  block/null: Enable 'read-zeroes' mode by default

 docs/devel/testing.rst                     | 14 +++++++-------
 tests/qtest/fuzz/generic_fuzz_configs.h    | 11 ++++++-----
 block/null.c                               |  2 +-
 tests/test-bdrv-drain.c                    | 10 ++++++++--
 tests/acceptance/virtio_check_params.py    |  2 +-
 tests/perf/block/qcow2/convert-blockstatus |  6 +++---
 tests/qemu-iotests/040                     |  2 +-
 tests/qemu-iotests/041                     | 12 ++++++++----
 tests/qemu-iotests/051                     |  2 +-
 tests/qemu-iotests/051.out                 |  2 +-
 tests/qemu-iotests/051.pc.out              |  4 ++--
 tests/qemu-iotests/087                     |  6 ++++--
 tests/qemu-iotests/118                     |  2 +-
 tests/qemu-iotests/133                     |  2 +-
 tests/qemu-iotests/153                     |  8 ++++----
 tests/qemu-iotests/184                     |  2 ++
 tests/qemu-iotests/184.out                 | 10 +++++-----
 tests/qemu-iotests/218                     |  3 +++
 tests/qemu-iotests/224                     |  3 ++-
 tests/qemu-iotests/224.out                 |  8 ++++----
 tests/qemu-iotests/225                     |  2 +-
 tests/qemu-iotests/227                     |  4 ++--
 tests/qemu-iotests/227.out                 |  4 ++--
 tests/qemu-iotests/228                     |  2 +-
 tests/qemu-iotests/235                     |  1 +
 tests/qemu-iotests/245                     |  2 +-
 tests/qemu-iotests/270                     |  2 +-
 tests/qemu-iotests/283                     |  3 ++-
 tests/qemu-iotests/283.out                 |  4 ++--
 tests/qemu-iotests/299                     |  1 +
 tests/qemu-iotests/299.out                 |  2 +-
 tests/qemu-iotests/300                     |  4 ++--
 32 files changed, 82 insertions(+), 60 deletions(-)

--=20
2.26.2