Coverity: drm_dp_mst_process_up_req(): Null pointer dereferences

[coverity-bot <keescook@chromium.org>]

Hello!

This is an experimental automated report about issues detected by Coverity
from a scan of next-20191031 as part of the linux-next weekly scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified
lines of code (noted below) that were touched by recent commits:

9408cc94eb04 ("drm/dp_mst: Handle UP requests asynchronously")

Coverity reported the following:

*** CID 1487392:  Null pointer dereferences  (FORWARD_NULL)
/drivers/gpu/drm/drm_dp_mst_topology.c: 3710 in drm_dp_mst_process_up_req()
3704
3705     		if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY)
3706     			guid = msg->u.conn_stat.guid;
3707     		else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
3708     			guid = msg->u.resource_stat.guid;
3709
vvv     CID 1487392:  Null pointer dereferences  (FORWARD_NULL)
vvv     Passing null pointer "guid" to "drm_dp_get_mst_branch_device_by_guid", which dereferences it.
3710     		mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
3711     	} else {
3712     		mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
3713     	}
3714
3715     	if (!mstb) {

If this is a false positive, please let us know so we can mark it as
such, or teach the Coverity rules to be smarter. If not, please make
sure fixes get into linux-next. :) For patches fixing this, please
include these lines (but double-check the "Fixes" first):

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1487392 ("Null pointer dereferences")
Fixes: 9408cc94eb04 ("drm/dp_mst: Handle UP requests asynchronously")


Thanks for your attention!

-- 
Coverity-bot