Hi!
From: Ziyang Xuan william.xuanziyang@huawei.com
Stopping tasklet and hrtimer rely on the active state of tasklet and hrtimer sequentially in bcm_remove_op(), the op object will be freed if they are all unactive. Assume the hrtimer timeout is short, the hrtimer cb has been excuted after tasklet conditional judgment which must be false after last round tasklet_kill() and before condition hrtimer_active(), it is false when execute to hrtimer_active(). Bug is triggerd, because the stopping action is end and the op object will be freed, but the tasklet is scheduled. The resources of the op object will occur UAF bug.
Move hrtimer_cancel() behind tasklet_kill() and switch 'while () {...}' to 'do {...} while ()' to fix the op UAF problem.
I don't see this commit in mainline or next kernels. What is going on here? Is it one of those "only needed in -stable" things? Or do we still need to fix it in the mainline?
Best regards, Pavel