On Fri, Feb 05, 2021 at 08:32:37AM -0500, Michael S. Tsirkin wrote:
On Fri, Feb 05, 2021 at 10:16:51AM +0100, Stefano Garzarella wrote:On Fri, Feb 05, 2021 at 11:27:32AM +0800, Jason Wang wrote: > > On 2021/2/5 上午1:22, Stefano Garzarella wrote: > > get_config() and set_config() callbacks in the 'struct vdpa_config_ops' > > usually already validated the inputs. Also now they can return an error, > > so we don't need to validate them here anymore. > > > > Let's use the return value of these callbacks and return it in case of > > error in vhost_vdpa_get_config() and vhost_vdpa_set_config(). > > > > Originally-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx> > > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> > > --- > > drivers/vhost/vdpa.c | 41 +++++++++++++---------------------------- > > 1 file changed, 13 insertions(+), 28 deletions(-) > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > index ef688c8c0e0e..d61e779000a8 100644 > > --- a/drivers/vhost/vdpa.c > > +++ b/drivers/vhost/vdpa.c > > @@ -185,51 +185,35 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp) > > return 0; > > } > > -static int vhost_vdpa_config_validate(struct vhost_vdpa *v, > > - struct vhost_vdpa_config *c) > > -{ > > - long size = 0; > > - > > - switch (v->virtio_id) { > > - case VIRTIO_ID_NET: > > - size = sizeof(struct virtio_net_config); > > - break; > > - } > > - > > - if (c->len == 0) > > - return -EINVAL; > > - > > - if (c->len > size - c->off) > > - return -E2BIG; > > - > > - return 0; > > -} > > - > > static long vhost_vdpa_get_config(struct vhost_vdpa *v, > > struct vhost_vdpa_config __user *c) > > { > > struct vdpa_device *vdpa = v->vdpa; > > struct vhost_vdpa_config config; > > unsigned long size = offsetof(struct vhost_vdpa_config, buf); > > + long ret; > > u8 *buf; > > if (copy_from_user(&config, c, size)) > > return -EFAULT; > > - if (vhost_vdpa_config_validate(v, &config)) > > + if (config.len == 0) > > return -EINVAL; > > buf = kvzalloc(config.len, GFP_KERNEL); > > > Then it means usersapce can allocate a very large memory. Good point. > > Rethink about this, we should limit the size here (e.g PAGE_SIZE) or > fetch the config size first (either through a config ops as you > suggested or a variable in the vdpa device that is initialized during > device creation). Maybe PAGE_SIZE is okay as a limit. If instead we want to fetch the config size, then better a config ops in my opinion, to avoid adding a new parameter to __vdpa_alloc_device(). I vote for PAGE_SIZE, but it isn't a strong opinion. What do you and @Michael suggest? Thanks, StefanoDevices know what the config size is. Just have them provide it.
Okay, I'll add get_config_size() callback in vdpa_config_ops and I'll leave vhost_vdpa_config_validate() that will use that callback instead of 'virtio_id' to get the config size from the device.
At this point I think I can remove the "vdpa: add return value to get_config/set_config callbacks" patch and leave void return to get_config/set_config callbacks.
Does this make sense? Thanks, Stefano
