CVE-2022-49309

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

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

There is a deadlock in rtwsurveydoneevent_callback(), which is shown below:

(Thread 1) | (Thread 2) | settimer() rtwsurveydoneeventcallback()| modtimer() spinlockbh() //(1) | (wait a time) ... | rtwscantimeouthandler() deltimersync() | spinlock_bh() //(2) (wait timer to stop) | ...

We hold pmlmepriv->lock in position (1) of thread 1 and use deltimersync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtwsurveydoneevent_callback() will block forever.

This patch extracts deltimersync() from the protection of spinlockbh(), which could let timer handler to obtain the needed lock. What`s more, we change spinlockbh() in rtwscantimeouthandler() to spinlockirq(). Otherwise, spinlock_bh() will also cause deadlock() in timer handler.