lkml.org 
[lkml]   [2021]   [Feb]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 09/13] vhost/vdpa: remove vhost_vdpa_config_validate()
    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

    \
     
     \ /
      Last update: 2021-02-05 10:25    [W:11.685 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site