Re: [PATCH] s390/vfio_ap: fix memory leak in vfio_ap device driver

[Anthony Krowiak]

On 3/16/23 4:39 AM, Heiko Carstens wrote:
> On Wed, Mar 15, 2023 at 11:39:32AM -0400, Tony Krowiak wrote:
> > The device release callback function invoked to release the matrix device
> > uses the dev_get_drvdata(device *dev) function to retrieve the
> > pointer to the vfio_matrix_dev object in order to free its storage. The
> > problem is, this object is not stored as drvdata with the device; since the
> > kfree function will accept a NULL pointer, the memory for the
> > vfio_matrix_dev object is never freed.
> >
> > Since the device being released is contained within the vfio_matrix_dev
> > object, the container_of macro will be used to retrieve its pointer.
> >
> > Fixes: 1fde573413b5 ("s390: vfio-ap: base implementation of VFIO AP device driver")
> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> > ---
> >   drivers/s390/crypto/vfio_ap_drv.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> > index 997b524bdd2b..15e9de9f4574 100644
> > --- a/drivers/s390/crypto/vfio_ap_drv.c
> > +++ b/drivers/s390/crypto/vfio_ap_drv.c
> > @@ -54,8 +54,9 @@ static struct ap_driver vfio_ap_drv = {
> >   
> >   static void vfio_ap_matrix_dev_release(struct device *dev)
> >   {
> > -	struct ap_matrix_dev *matrix_dev = dev_get_drvdata(dev);
> > -
> > +	struct ap_matrix_dev *matrix_dev = container_of(dev,
> > +							struct ap_matrix_dev,
> > +							device);
> >   	kfree(matrix_dev);
> Could you keep this code more readable, including adding the missing
> blank line after the declaration, please? Something like:
>
> static void vfio_ap_matrix_dev_release(struct device *dev)
> {
> 	struct ap_matrix_dev *matrix_dev;
>
> 	matrix_dev = container_of(dev, struct ap_matrix_dev, device);
> 	kfree(matrix_dev);
> }
>
> Thanks!


Will do.