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Re: [PATCH] virtio-serial-bus: do cleanup on the error path in realize()
From: |
Pan Nengyuan |
Subject: |
Re: [PATCH] virtio-serial-bus: do cleanup on the error path in realize() to avoid memleaks |
Date: |
Thu, 5 Mar 2020 11:13:54 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 |
On 3/4/2020 5:23 PM, Markus Armbruster wrote:
> Pan Nengyuan <address@hidden> writes:
>
>> port->bh forgot to delete on the error path, this patch add it to fix
>> memleaks. It's easy to reproduce as follow(add a same nr port):
>> {'execute': 'device_add', 'arguments': {'id': 'virtio_serial_pci0',
>> 'driver': 'virtio-serial-pci', 'bus': 'pci.0', 'addr': '0x5'}, 'id':
>> 'yVkZcGgV'}
>> {'execute': 'device_add', 'arguments': {'id': 'port1', 'driver':
>> 'virtserialport', 'name': 'port1', 'chardev': 'channel1', 'bus':
>> 'virtio_serial_pci0.0', 'nr': 1}, 'id': '3dXdUgJA'}
>> {'execute': 'device_add', 'arguments': {'id': 'port2', 'driver':
>> 'virtserialport', 'name': 'port2', 'chardev': 'channel2', 'bus':
>> 'virtio_serial_pci0.0', 'nr': 1}, 'id': 'qLzcCkob'}
>> {'execute': 'device_add', 'arguments': {'id': 'port2', 'driver':
>> 'virtserialport', 'name': 'port2', 'chardev': 'channel2', 'bus':
>> 'virtio_serial_pci0.0', 'nr': 2}, 'id': 'qLzcCkob'}
>>
>> The leak stack:
>> Direct leak of 40 byte(s) in 1 object(s) allocated from:
>> #0 0x7f04a8008ae8 in __interceptor_malloc (/lib64/libasan.so.5+0xefae8)
>> #1 0x7f04a73cf1d5 in g_malloc (/lib64/libglib-2.0.so.0+0x531d5)
>> #2 0x56273eaee484 in aio_bh_new /mnt/sdb/backup/qemu/util/async.c:125
>> #3 0x56273eafe9a8 in qemu_bh_new
>> /mnt/sdb/backup/qemu/util/main-loop.c:532
>> #4 0x56273d52e62e in virtser_port_device_realize
>> /mnt/sdb/backup/qemu/hw/char/virtio-serial-bus.c:946
>> #5 0x56273dcc5040 in device_set_realized
>> /mnt/sdb/backup/qemu/hw/core/qdev.c:891
>> #6 0x56273e5ebbce in property_set_bool
>> /mnt/sdb/backup/qemu/qom/object.c:2238
>> #7 0x56273e5e5a9c in object_property_set
>> /mnt/sdb/backup/qemu/qom/object.c:1324
>> #8 0x56273e5ef5f8 in object_property_set_qobject
>> /mnt/sdb/backup/qemu/qom/qom-qobject.c:26
>> #9 0x56273e5e5e6a in object_property_set_bool
>> /mnt/sdb/backup/qemu/qom/object.c:1390
>> #10 0x56273daa40de in qdev_device_add
>> /mnt/sdb/backup/qemu/qdev-monitor.c:680
>> #11 0x56273daa53e9 in qmp_device_add
>> /mnt/sdb/backup/qemu/qdev-monitor.c:805
>>
>> Reported-by: Euler Robot <address@hidden>
>> Signed-off-by: Pan Nengyuan <address@hidden>
>
> Fixes: 199646d81522509ac2dba6d28c31e8c7d807bc93
>
>> ---
>> hw/char/virtio-serial-bus.c | 14 +++++++++-----
>> 1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
>> index 941ed5aca9..563b845f71 100644
>> --- a/hw/char/virtio-serial-bus.c
>> +++ b/hw/char/virtio-serial-bus.c
>> @@ -957,13 +957,13 @@ static void virtser_port_device_realize(DeviceState
>> *dev, Error **errp)
>> if (find_port_by_id(port->vser, port->id)) {
>> error_setg(errp, "virtio-serial-bus: A port already exists at id
>> %u",
>> port->id);
>> - return;
>> + goto fail;
>> }
>>
>> if (port->name != NULL && find_port_by_name(port->name)) {
>> error_setg(errp, "virtio-serial-bus: A port already exists by name
>> %s",
>> port->name);
>> - return;
>> + goto fail;
>> }
>>
>> if (port->id == VIRTIO_CONSOLE_BAD_ID) {
>> @@ -974,7 +974,7 @@ static void virtser_port_device_realize(DeviceState
>> *dev, Error **errp)
>> if (port->id == VIRTIO_CONSOLE_BAD_ID) {
>> error_setg(errp, "virtio-serial-bus: Maximum port limit for
>> "
>> "this device reached");
>> - return;
>> + goto fail;
>> }
>> }
>> }
>> @@ -983,16 +983,20 @@ static void virtser_port_device_realize(DeviceState
>> *dev, Error **errp)
>> if (port->id >= max_nr_ports) {
>> error_setg(errp, "virtio-serial-bus: Out-of-range port id
>> specified, "
>> "max. allowed: %u", max_nr_ports - 1);
>> - return;
>> + goto fail;
>> }
>>
>> vsc->realize(dev, &err);
>> if (err != NULL) {
>> error_propagate(errp, err);
>> - return;
>> + goto fail;
>> }
>>
>> port->elem = NULL;
>> + return;
>> +
>> +fail:
>> + qemu_bh_delete(port->bh);
>> }
>>
>> static void virtser_port_device_plug(HotplugHandler *hotplug_dev,
>
> Looks correct to me.
>
> However, I wonder whether we could simply create port->bh later. It's
> for use by virtio_serial_throttle_port(), called on incoming migration
> via virtio_serial_load_device(), virtio_load(), virtio_device_get(). It
> runs flush_queued_data(), which does nothing unless
> virtio_queue_ready(port->ovq).
>
> Note that virtio_queue_ready() dereferences its argument. It's safe
> only after virtser_port_device_plug() set port->ovq. I'd expect that to
> be possible only while the device is realized. If that's correct, we
> could simply create port->bh last in virtser_port_device_realize().
Yes, it looks correct. If there is no other points, I will change it.
Thanks.
>
> .
>