Re: [Xen-devel] [PATCH v2] xen: use qdev_unplug() instead of g_free() in xen_pv_find_xendev()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Hi Peter,

do you think this is acceptable?

Thanks,

Stefano

On Wed, 1 Feb 2017, Juergen Gross wrote:
> The error exits of xen_pv_find_xendev() free the new xen-device via
> g_free() which is wrong.
> 
> As the xen-device has been initialized as qdev it must be removed
> via qdev_unplug().
> 
> This bug has been introduced with commit 3a6c9172ac5951e6dac2b3f6
> ("xen: create qdev for each backend device").
> 
> Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Tested-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V2: set free method to avoid memory leak (Peter Maydell)
>     use DEVICE(xendev) instead of &xendev->qdev (Peter Maydell)
> ---
>  hw/xen/xen_backend.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
> index d119004..6c21c37 100644
> --- a/hw/xen/xen_backend.c
> +++ b/hw/xen/xen_backend.c
> @@ -124,10 +124,11 @@ static struct XenDevice *xen_be_get_xendev(const char 
> *type, int dom, int dev,
>      /* init new xendev */
>      xendev = g_malloc0(ops->size);
>      object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
> -    qdev_set_parent_bus(&xendev->qdev, xen_sysbus);
> -    qdev_set_id(&xendev->qdev, g_strdup_printf("xen-%s-%d", type, dev));
> -    qdev_init_nofail(&xendev->qdev);
> -    object_unref(OBJECT(&xendev->qdev));
> +    OBJECT(xendev)->free = g_free;
> +    qdev_set_parent_bus(DEVICE(xendev), xen_sysbus);
> +    qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev));
> +    qdev_init_nofail(DEVICE(xendev));
> +    object_unref(OBJECT(xendev));
>  
>      xendev->type  = type;
>      xendev->dom   = dom;
> @@ -145,7 +146,7 @@ static struct XenDevice *xen_be_get_xendev(const char 
> *type, int dom, int dev,
>      xendev->evtchndev = xenevtchn_open(NULL, 0);
>      if (xendev->evtchndev == NULL) {
>          xen_pv_printf(NULL, 0, "can't open evtchn device\n");
> -        g_free(xendev);
> +        qdev_unplug(DEVICE(xendev), NULL);
>          return NULL;
>      }
>      fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
> @@ -155,7 +156,7 @@ static struct XenDevice *xen_be_get_xendev(const char 
> *type, int dom, int dev,
>          if (xendev->gnttabdev == NULL) {
>              xen_pv_printf(NULL, 0, "can't open gnttab device\n");
>              xenevtchn_close(xendev->evtchndev);
> -            g_free(xendev);
> +            qdev_unplug(DEVICE(xendev), NULL);
>              return NULL;
>          }
>      } else {
> -- 
> 2.10.2
>

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