Re: [PATCH] virtio-9p-device: fix memleak in virtio_9p_device_unrealize

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Dienstag, 14. Januar 2020 11:08:59 CET Christian Schoenebeck wrote:
> On Dienstag, 14. Januar 2020 08:40:20 CET pannengyuan@huawei.com wrote:
> > From: Pan Nengyuan <pannengyuan@huawei.com>
> > 
> > v->vq forgot to cleanup in virtio_9p_device_unrealize, the memory leak
> > stack is as follow:
> > 
> > Direct leak of 14336 byte(s) in 2 object(s) allocated from:
> >   #0 0x7f819ae43970 (/lib64/libasan.so.5+0xef970)  ??:?
> >   #1 0x7f819872f49d (/lib64/libglib-2.0.so.0+0x5249d)  ??:?
> >   #2 0x55a3a58da624 (./x86_64-softmmu/qemu-system-x86_64+0x2c14624)
> > 
> > /mnt/sdb/qemu/hw/virtio/virtio.c:2327 #3 0x55a3a571bac7
> > (./x86_64-softmmu/qemu-system-x86_64+0x2a55ac7)
> > /mnt/sdb/qemu/hw/9pfs/virtio-9p-device.c:209 #4 0x55a3a58e7bc6
> > (./x86_64-softmmu/qemu-system-x86_64+0x2c21bc6)
> > /mnt/sdb/qemu/hw/virtio/virtio.c:3504 #5 0x55a3a5ebfb37
> > (./x86_64-softmmu/qemu-system-x86_64+0x31f9b37)
> > /mnt/sdb/qemu/hw/core/qdev.c:876
> > 
> > Reported-by: Euler Robot <euler.robot@huawei.com>
> > Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
> > ---
> > 
> >  hw/9pfs/virtio-9p-device.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
> > index b5a7c03f26..b146387ae2 100644
> > --- a/hw/9pfs/virtio-9p-device.c
> > +++ b/hw/9pfs/virtio-9p-device.c
> > @@ -215,6 +215,7 @@ static void virtio_9p_device_unrealize(DeviceState
> > *dev, Error **errp) V9fsVirtioState *v = VIRTIO_9P(dev);
> > 
> >      V9fsState *s = &v->state;
> > 
> > +    virtio_delete_queue(v->vq);
> > 
> >      virtio_cleanup(vdev);
> >      v9fs_device_unrealize_common(s, errp);
> >  
> >  }
> 
> Looks like you are using an old interface. The new one is
> 
> 	void virtio_del_queue(VirtIODevice *vdev, int n);

Ah, my bad, it is actually the other way around, that is I was not up to date; 
virtio_delete_queue() was apparently introduced a week ago:
https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg00723.html

The old virtio_del_queue() still exists though:
https://github.com/qemu/qemu/blob/master/hw/virtio/virtio.c#L2339

Having said that, it would probably still make sense to use virtio_del_queue() 
instead for now to make it easier for stable branches to merge this fix?

Best regards,
Christian Schoenebeck