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://nvd.nist.gov/vuln/detail/CVE-2022-49309
• https://git.kernel.org/stable/c/2c41f5c341853f84b7bc2f32605d4e2782e8c279
• https://git.kernel.org/stable/c/cc7ad0d77b51c872d629bcd98aea463a3c4109e7
• https://git.kernel.org/stable/c/ce129d3efd181da5fd56f4360cc8827122afa67e
• https://git.kernel.org/stable/c/f89f6c3ebf69623b8ea48200bd690e9e210335a1
• https://git.kernel.org/stable/c/c84e5c819600ee0628f61b33d145258ae0f3d7a7