In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix races in cifsd thread creation

The cifsd demultiplex thread can run and access tcp ses before the parent thread has finished populating tcp ses, which the worker thread accesses locklessly.

Also, the kthread run macro may start the thread before returning the thread pointer. Because the pointer is part of the structure that the thread can access, if the kernel is preempted after the thread is spawned, but before the thread pointer is populated and the thread attempts to exit, it will sleep, waiting for a SIGKILL signal.

Fix this by moving creation of the thread to after all of tcp ses'es fields are populated, and spawning the thread last, using a split kthread create/wake up process logic.