drivers: staging: rtl8723bs: Fix deadlock in rtw_surveydone_event_callback()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8723bs: Fix deadlock in rtw_surveydone_event_callback() There is a deadlock in rtw_surveydone_event_callback(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_surveydone_event_callback()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_scan_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ... We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_surveydone_event_callback() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() in rtw_scan_timeout_handler() to spin_lock_irq(). Otherwise, spin_lock_bh() will also cause deadlock() in timer handler.

References

• https://git.kernel.org/stable/c/c84e5c819600ee0628f61b33d145258ae0f3d7a7
• https://git.kernel.org/stable/c/f89f6c3ebf69623b8ea48200bd690e9e210335a1
• https://git.kernel.org/stable/c/ce129d3efd181da5fd56f4360cc8827122afa67e
• https://git.kernel.org/stable/c/2c41f5c341853f84b7bc2f32605d4e2782e8c279
• https://git.kernel.org/stable/c/cc7ad0d77b51c872d629bcd98aea463a3c4109e7