CVE-2025-38352 PoC — posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

Source

https://github.com/farazsth98/poc-CVE-2025-38352

Associated Vulnerability

Title: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() (CVE-2025-38352)
Description:In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.

Description

This is a proof of concept for CVE-2025-38352, a vulnerability in the Linux kernel's POSIX CPU timers implementation. The September 2025 Android Bulletin mentions that this vulnerability has been used in limited, targeted exploitation in the wild.

File Snapshot

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