CVE-2022-49311drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle()

Official description

In the Linux kernel, the following vulnerability has been resolved: drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle() There is a deadlock in rtw_joinbss_event_prehandle(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_joinbss_event_prehandle()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | _rtw_join_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_joinbss_event_prehandle() 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() to spin_lock_irq() in _rtw_join_timeout_handler() in order to prevent deadlock.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/ae60744d5fad840b9d056d35b4b652d95e755846
• https://git.kernel.org/stable/c/1f6c99b94ca3caad346876b3e22e3ca3d25bc8ee
• https://git.kernel.org/stable/c/eca9748d9267a38d532464e3305a38629e9c35a9
• https://git.kernel.org/stable/c/041879b12ddb0c6c83ed9c0bdd10dc82a056f2fc