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,
Stefano
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