Commit 5c647926 authored Oct 24, 2016 by Syed Rameez Mustafa

sched: Set curr/prev_window_cpu pointers to NULL in sched_exit()



trace_sched_update_task_ravg relies on NULL pointers to ensure that
it doesn't access them. Make sure that when a task exits, these
pointers are set to NULL. Otherwise any call to update_task_ravg()
between sched_exit() and releasing the task structure will access
bogus pointers. In some cases those memory locations are unmapped
and cause a kernel panic.

Change-Id: I9eebb4fb35aca2c8424bfb29ae9d833650dc5ad4
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>

parent 46aa49c1

kernel/sched/core.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -2273,6 +2273,14 @@ void sched_exit(struct task_struct *p)
		kfree(p->ravg.curr_window_cpu);
		kfree(p->ravg.prev_window_cpu);

		/*
		* update_task_ravg() can be called for exiting tasks. While the
		* function itself ensures correct behavior, the corresponding
		* trace event requires that these pointers be NULL.
		*/
		p->ravg.curr_window_cpu = NULL;
		p->ravg.prev_window_cpu = NULL;

		enqueue_task(rq, p, 0);
		clear_ed_task(p, rq);
		task_rq_unlock(rq, p, &flags);