Bluetooth: Fix race condition in hidp_session_thread

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix race condition in hidp_session_thread There is a potential race condition in hidp_session_thread that may lead to use-after-free. For instance, the timer is active while hidp_del_timer is called in hidp_session_thread(). After hidp_session_put, then 'session' will be freed, causing kernel panic when hidp_idle_timeout is running. The solution is to use del_timer_sync instead of del_timer. Here is the call trace: ? hidp_session_probe+0x780/0x780 call_timer_fn+0x2d/0x1e0 __run_timers.part.0+0x569/0x940 hidp_session_probe+0x780/0x780 call_timer_fn+0x1e0/0x1e0 ktime_get+0x5c/0xf0 lapic_next_deadline+0x2c/0x40 clockevents_program_event+0x205/0x320 run_timer_softirq+0xa9/0x1b0 __do_softirq+0x1b9/0x641 __irq_exit_rcu+0xdc/0x190 irq_exit_rcu+0xe/0x20 sysvec_apic_timer_interrupt+0xa1/0xc0