Messages in this thread |  | | Date | Fri, 5 Feb 2021 10:16:51 +0100 | From | Stefano Garzarella <> | Subject | Re: [PATCH v3 09/13] vhost/vdpa: remove vhost_vdpa_config_validate() |
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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
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