Re: IB/core: Use GID table in AH creation and dmac resolution

[Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

On 11/3/2015 3:11 PM, Dan Carpenter wrote:
> Hello Matan Barak,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch dbf727de7440: "IB/core: Use GID table in AH creation and
> dmac resolution" from Oct 15, 2015, leads to the following Smatch
> complaint:
>
> drivers/infiniband/hw/ocrdma/ocrdma_ah.c:157 ocrdma_create_ah()
> 	 error: we previously assumed 'sgid_attr.ndev' could be null (see line 146)
>
> drivers/infiniband/hw/ocrdma/ocrdma_ah.c
>     145		}
>     146		if (sgid_attr.ndev) {
>                      ^^^^^^^^^^^^^^
> Patch introduces a NULL check.
>
>     147			if (is_vlan_dev(sgid_attr.ndev))
>     148				vlan_tag = vlan_dev_vlan_id(sgid_attr.ndev);
>     149			dev_put(sgid_attr.ndev);
>     150		}
>     151	
>     152		if ((pd->uctx) &&
>     153		    (!rdma_is_multicast_addr((struct in6_addr *)attr->grh.dgid.raw)) &&
>     154		    (!rdma_link_local_addr((struct in6_addr *)attr->grh.dgid.raw))) {
>     155			status = rdma_addr_find_dmac_by_grh(&sgid, &attr->grh.dgid,
>     156							    attr->dmac, &vlan_tag,
>     157							    sgid_attr.ndev->ifindex);
>                                                              ^^^^^^^^^^^^^^^^
> Patch introduces this new dereference.  The warning might be a false
> positive if "pd->uctx" or rdma_is_multicast_addr() imply it's non-NULL
> but I don't know this code well enough to say for sure.  Hence this
> email.  :)
>
>     158			if (status) {
>     159				pr_err("%s(): Failed to resolve dmac from gid."
>
> regards,
> dan carpenter
>

Thanks for the catch Dan.
As I wrote in the commit message - "ocrdma driver changes were done by 
Somnath Kotur <Somnath.Kotur-idTK6quXuVSLFuii7jzJGg@public.gmane.org>"
Somnath, RoCE implies non-NULL ndev, but dereferencing ifindex after 
dev_put doesn't seem to be safe.
Could you please take a look?

Thanks,
Matan

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html