Messages in this thread |  | | Subject | Re: [PATCH v3 09/13] vhost/vdpa: remove vhost_vdpa_config_validate() | From | Jason Wang <> | Date | Mon, 8 Feb 2021 12:13:23 +0800 |
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On 2021/2/5 下午10:17, Stefano Garzarella wrote: > 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@bytedance.com> >>> > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> >>> > > --- >>> > > 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, >>> Stefano >> >> Devices 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
Yes I think so.
Thanks
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