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ax25: fix use-after-free bugs caused by ax25_ds_del_timer

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When the ax25 device is detaching, the ax25_dev_device_down()
calls ax25_ds_del_timer() to cleanup the slave_timer. When
the timer handler is running, the ax25_ds_del_timer() that
calls del_timer() in it will return directly. As a result,
the use-after-free bugs could happen, one of the scenarios
is shown below:

      (Thread 1)          |      (Thread 2)
                          | ax25_ds_timeout()
ax25_dev_device_down()    |
  ax25_ds_del_timer()     |
    del_timer()           |
  ax25_dev_put() //FREE   |
                          |  ax25_dev-> //USE

In order to mitigate bugs, when the device is detaching, use
timer_shutdown_sync() to stop the timer.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240329015023.9223-1-duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Duoming Zhou 2024-03-29 09:50:23 +08:00 committed by Jakub Kicinski
parent ea2a1cfc3b
commit fd819ad3ec
1 changed files with 1 additions and 1 deletions
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2
net/ax25/ax25_dev.c
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@ -105,7 +105,7 @@ void ax25_dev_device_down(struct net_device *dev)
spin_lock_bh(&ax25_dev_lock);
#ifdef CONFIG_AX25_DAMA_SLAVE
ax25_ds_del_timer(ax25_dev);
timer_shutdown_sync(&ax25_dev->dama.slave_timer);
#endif
/*