iotests/283: Check that finalize drops backup-top

Without any of HEAD^ or HEAD^^ applied, qemu will most likely crash on
the qemu-io invocation, for a variety of immediate reasons.  The
underlying problem is generally a use-after-free access into
backup-top's BlockCopyState.

With only HEAD^ applied, qemu-io will run into an EIO (which is not
capture by the output, but you can see that the qemu-io invocation will
be accepted (i.e., qemu-io will run) in contrast to the reference
output, where the node name cannot be found), and qemu will then crash
in query-named-block-nodes: bdrv_get_allocated_file_size() detects
backup-top to be a filter and passes the request through to its child.
However, after bdrv_backup_top_drop(), that child is NULL, so the
recursive call crashes.

With HEAD^^ applied, this test should pass.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210219153348.41861-4-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2021-02-19 16:33:48 +01:00 committed by Kevin Wolf
parent 705dde27c6
commit e417994092
2 changed files with 68 additions and 0 deletions

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@ -97,3 +97,56 @@ vm.qmp_log('blockdev-add', **{
vm.qmp_log('blockdev-backup', sync='full', device='source', target='target')
vm.shutdown()
print('\n=== backup-top should be gone after job-finalize ===\n')
# Check that the backup-top node is gone after job-finalize.
#
# During finalization, the node becomes inactive and can no longer
# function. If it is still present, new parents might be attached, and
# there would be no meaningful way to handle their I/O requests.
vm = iotests.VM()
vm.launch()
vm.qmp_log('blockdev-add', **{
'node-name': 'source',
'driver': 'null-co',
})
vm.qmp_log('blockdev-add', **{
'node-name': 'target',
'driver': 'null-co',
})
vm.qmp_log('blockdev-backup',
job_id='backup',
device='source',
target='target',
sync='full',
filter_node_name='backup-filter',
auto_finalize=False,
auto_dismiss=False)
vm.event_wait('BLOCK_JOB_PENDING', 5.0)
# The backup-top filter should still be present prior to finalization
assert vm.node_info('backup-filter') is not None
vm.qmp_log('job-finalize', id='backup')
vm.event_wait('BLOCK_JOB_COMPLETED', 5.0)
# The filter should be gone now. Check that by trying to access it
# with qemu-io (which will most likely crash qemu if it is still
# there.).
vm.qmp_log('human-monitor-command',
command_line='qemu-io backup-filter "write 0 1M"')
# (Also, do an explicit check.)
assert vm.node_info('backup-filter') is None
vm.qmp_log('job-dismiss', id='backup')
vm.event_wait('JOB_STATUS_CHANGE', 5.0, {'data': {'status': 'null'}})
vm.shutdown()

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@ -6,3 +6,18 @@
{"return": {}}
{"execute": "blockdev-backup", "arguments": {"device": "source", "sync": "full", "target": "target"}}
{"error": {"class": "GenericError", "desc": "Cannot set permissions for backup-top filter: Conflicts with use by other as 'image', which uses 'write' on base"}}
=== backup-top should be gone after job-finalize ===
{"execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "source"}}
{"return": {}}
{"execute": "blockdev-add", "arguments": {"driver": "null-co", "node-name": "target"}}
{"return": {}}
{"execute": "blockdev-backup", "arguments": {"auto-dismiss": false, "auto-finalize": false, "device": "source", "filter-node-name": "backup-filter", "job-id": "backup", "sync": "full", "target": "target"}}
{"return": {}}
{"execute": "job-finalize", "arguments": {"id": "backup"}}
{"return": {}}
{"execute": "human-monitor-command", "arguments": {"command-line": "qemu-io backup-filter \"write 0 1M\""}}
{"return": "Error: Cannot find device= nor node_name=backup-filter\r\n"}
{"execute": "job-dismiss", "arguments": {"id": "backup"}}
{"return": {}}