[bug report] vxlan: add adjacent link to limit depth level

[bug report] vxlan: add adjacent link to limit depth level

[Dan Carpenter]

Hello Taehee Yoo,

This is a semi-automatic email about new static checker warnings.

The patch 0ce1822c2a08: "vxlan: add adjacent link to limit depth
level" from Oct 21, 2019, leads to the following Smatch complaint:

    drivers/net/vxlan.c:4012 vxlan_changelink()
    error: we previously assumed 'lowerdev' could be null (see line 4009)

drivers/net/vxlan.c
  4008		netdev_adjacent_change_commit(dst->remote_dev, lowerdev, dev);
  4009		if (lowerdev && lowerdev != dst->remote_dev)
                    ^^^^^^^^
The patch adds a check for NULL,

  4010			dst->remote_dev = lowerdev;
  4011	
  4012		netdev_update_lockdep_key(lowerdev);
                                          ^^^^^^^^
but it also adds a new unchecked dereference (inside the function).

  4013		vxlan_config_apply(dev, &conf, lowerdev, vxlan->net, true);
  4014		return 0;

regards,
dan carpenter

Re: [bug report] vxlan: add adjacent link to limit depth level

[Taehee Yoo]

On Tue, 29 Oct 2019 at 23:52, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>

Hi Dan!

> Hello Taehee Yoo,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 0ce1822c2a08: "vxlan: add adjacent link to limit depth
> level" from Oct 21, 2019, leads to the following Smatch complaint:
>
>     drivers/net/vxlan.c:4012 vxlan_changelink()
>     error: we previously assumed 'lowerdev' could be null (see line 4009)
>
> drivers/net/vxlan.c
>   4008          netdev_adjacent_change_commit(dst->remote_dev, lowerdev, dev);
>   4009          if (lowerdev && lowerdev != dst->remote_dev)
>                     ^^^^^^^^
> The patch adds a check for NULL,
>
>   4010                  dst->remote_dev = lowerdev;
>   4011
>   4012          netdev_update_lockdep_key(lowerdev);
>                                           ^^^^^^^^
> but it also adds a new unchecked dereference (inside the function).
>
>   4013          vxlan_config_apply(dev, &conf, lowerdev, vxlan->net, true);
>   4014          return 0;
>

Thank you very much for reporting this bug.
While I'm taking look at this bug, I found a more serious bug that is
to break existing configuration.
Anyway, I will fix this bug as soon as possible.

Thank you so much again,
Taehee Yoo

> regards,
> dan carpenter