CVE-2024-35887

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

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

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.