net: wwan: t7xx: Fix FSM command timeout issue

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: wwan: t7xx: Fix FSM command timeout issue When driver processes the internal state change command, it use an asynchronous thread to process the command operation. If the main thread detects that the task has timed out, the asynchronous thread will panic when executing the completion notification because the main thread completion object has been released. BUG: unable to handle page fault for address: fffffffffffffff8 PGD 1f283a067 P4D 1f283a067 PUD 1f283c067 PMD 0 Oops: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:complete_all+0x3e/0xa0 [...] Call Trace: <TASK> ? __die_body+0x68/0xb0 ? page_fault_oops+0x379/0x3e0 ? exc_page_fault+0x69/0xa0 ? asm_exc_page_fault+0x22/0x30 ? complete_all+0x3e/0xa0 fsm_main_thread+0xa3/0x9c0 [mtk_t7xx (HASH:1400 5)] ? __pfx_autoremove_wake_function+0x10/0x10 kthread+0xd8/0x110 ? __pfx_fsm_main_thread+0x10/0x10 [mtk_t7xx (HASH:1400 5)] ? __pfx_kthread+0x10/0x10 ret_from_fork+0x38/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> [...] CR2: fffffffffffffff8 ---[ end trace 0000000000000000 ]--- Use the reference counter to ensure safe release as Sergey suggests: https://lore.kernel.org/all/da90f64c-260a-4329-87bf-1f9ff20a5951@gmail.com/

References

• https://git.kernel.org/stable/c/b8ab9bd0c8855cd5a6f4e0265083576257ff3fc5
• https://git.kernel.org/stable/c/0cd3bde081cd3452c875fa1e5c55834c670d6e05
• https://git.kernel.org/stable/c/e6e6882a1590cbdaca77a31a02f4954327237e14
• https://git.kernel.org/stable/c/4f619d518db9cd1a933c3a095a5f95d0c1584ae8