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

drivers: staging: rtl8192e: Fix deadlock in rtllib_beacons_stop()

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

   (Thread 1)              |      (Thread 2)
                           | rtllib_send_beacon()
rtllib_beacons_stop()      |  mod_timer()
 spin_lock_irqsave() //(1) |  (wait a time)
 ...                       | rtllib_send_beacon_cb()
 del_timer_sync()          |  spin_lock_irqsave() //(2)
 (wait timer to stop)      |  ...

We hold ieee->beacon_lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need ieee->beacon_lock in position (2) of thread 2.
As a result, rtllib_beacons_stop() will block forever.

This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain
the needed lock.

https://git.kernel.org/stable/c/08bacf871c019163ccd1389d0bc957a43324967a

https://git.kernel.org/stable/c/0f69d7d5e918aa43423d86bd17ddb11b1b5e8ada

https://git.kernel.org/stable/c/381045dc64d23a2229c47c5524c06bfc33d34446

https://git.kernel.org/stable/c/4681129fda9e8555392eaaadb239ec6a6e2b3e12

https://git.kernel.org/stable/c/46c861009bf437a18417df24cea0d181741b7d72

https://git.kernel.org/stable/c/64b05fa212c7e4d057676e8b7e7120c6eb2f615b

https://git.kernel.org/stable/c/9b6bdbd9337de3917945847bde262a34a87a6303

https://git.kernel.org/stable/c/fef451f0fbbe85dbd2962b18379d02e2965610db

https://git.kernel.org/stable/c/ffd4c4d5293e4985092ea45ba21cad9326e2e434