Description: uwb: properly check kthread_run return value
References:
Notes:
 bwh> This doesn't seem like a security flaw, just a dumb bug.  It's
 bwh> also mitigated by the total irrelevance of UWB.  Introduced
 bwh> in 2.6.28 by commit 183b9b592a62 "uwb: add the UWB stack (core
 bwh> files)".
Bugs:
upstream: released (4.14-rc4) [bbf26183b7a6236ba602f4d6a2f7cade35bba043]
4.9-upstream-stable: released (4.9.55) [8ff7adb930d4a62f43dfc76220a988a043c510ff]
3.16-upstream-stable: released (3.16.52) [8a088612bc35033159077fa7bee6f3761d712725]
3.2-upstream-stable: released (3.2.97) [c95d921ebf9e02853bd090f3b3845085082185f8]
sid: released (4.13.10-1)
4.9-stretch-security: released (4.9.65-1)
3.16-jessie-security: released (3.16.56-1)
3.2-wheezy-security: released (3.2.101-1)