commit c793bbfc4a0a9f5a66978fc91559e9681748dbeb upstream.
When timers are migrated away from an offline CPU the debugobjects state
gets corrupted. The timer is accounted as inactive on deletion, but the
enqueue on the alive CPU lacks the activation call.
That used to work, but got broken when the trace point and the debug
objects call got separated. That change missed to fixup
migrate_timer_list().
Add the missing debug_timer_activate() invocation to fix it.
Fixes: dc1e7dc5ac62 ("timer: Move trace point to get proper index")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/87bjb0l7ha.ffs@fw13
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4b61084b11bcecce86d03804ff30f8d7b465593c upstream.
If the auxiliary clock is disabled during tk_get_aux_ts64() but is enabled
before tks->clock_valid is checked, then uninitialized stackdata will be
used in the calculations and indirectly leaked to userspace.
The same race window also exists after this change and also for the core
timekeeper. But in these cases the only effect would be incorrect
adjustments and this is userspace's responsibility to avoid this.
Fixes: 4eca49d0b621 ("timekeeping: Prepare do_adtimex() for auxiliary clocks")
Signed-off-by: Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260731-timekeeping-aux-adjtimex-return-v1-1-b7fea4692886@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 18c7d85864e554adc8fad1e8d2e9d2cb6c3911c8 upstream. On native sparc64, struct __kernel_old_timeval contains a four-byte hole after tv_usec because tv_sec is 64-bit while __kernel_suseconds_t is 32-bit. put_itimerval() fills only the named fields in a stack-allocated __kernel_old_itimerval and copies the entire object to userspace, so getitimer() can expose the two padding holes. Zero-initialize the aggregate before assigning the fields so implicit padding is deterministic before it crosses the user/kernel boundary. Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Assisted-by: Codex:gpt-5 Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260809190428.1523014-1-Jeremy.Jean@oss.cyber.gouv.fr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Wongi and Jungwoo decoded and reported a non-leader exec() related race
which can result in an UAF:
sys_timer_delete() exec()
posix_cpu_timer_del()
// Observes old leader
p = pid_task(pid, pid_type); de_thread()
switch_leader();
release_task(old_leader)
__exit_signal(old_leader)
sighand = lock(old_leader, sighand);
posix_cpu_timers*_exit();
sighand = lock_task_sighand(p) unhash_task(old_leader);
sh = lock(p, sighand) old_leader->sighand = NULL;
unlock(sighand);
(p->sighand == NULL)
unlock(sh)
return NULL;
// Returns without action
if(!sighand)
return 0;
free_posix_timer();
This is "harmless" unless the deleted timer was armed and enqueued in
p->signal because on exec() a TGID targeted timer is inherited.
As sys_timer_delete() freed the underlying posix timer object
run_posix_cpu_timers() or any timerqueue related add/delete operations on
other timers will access the freed object's timerqueue node, which results
in an UAF.
There is a similar problem vs. posix_cpu_timer_set(). For regular posix
timers it just transiently returns -ESRCH to user space, but for the use
case in do_cpu_nanosleep() it's the same UAF just that the k_itimer is
allocated on the stack.
Also posix_cpu_timer_rearm() fails to rearm the timer, which means it stops
to expire.
While debating solutions Frederic pointed out another problem:
posix_cpu_timer_del(tmr)
__exit_signal(p)
posix_cpu_timers*_exit(p);
unhash_task(p);
p->sighand = NULL;
sh = lock_task_sighand(p)
sighand = p->sighand;
if (!sighand)
return NULL;
lock(sighand);
if (!sh)
WARN_ON_ONCE(timer_queued(tmr));
On weakly ordered architectures it is not guaranteed that
posix_cpu_timer_del() will observe the stores in posix_cpu_timers*_exit()
when p->sighand is observed as NULL, which means the WARN() can be a false
positive.
Solve these issues by:
1) Changing the store in __exit_signal() to smp_store_release().
2) Adding a smp_acquire__after_ctrl_dep() into the !sighand path
of lock_task_sighand().
3) Creating a helper function for looking up the task and locking sighand
which does not return when sighand == NULL. Instead it retries the
task lookup and only if that fails it gives up.
4) Using that helper in the three affected functions.
#1/#2 ensures that the reader side which observes sighand == NULL also
observes all preceeding stores, i.e. the stores in posix_cpu_timers*_exit()
and the ones in unhash_task().
#3 ensures that the above described non-leader exec() situation is handled
gracefully. When the task lookup returns the old leader, but sighand ==
NULL then it retries. In the non-leader exec() case the subsequent task
lookup will observe the new leader due to #1/#2. In normal exit() scenarios
the subsequent lookup fails.
When the task lookup fails, the function also checks whether the timer is
still enqueued and issues a warning if that's the case. Unfortunately there
is nothing which can be done about it, but as the task is already not
longer visible the timer should not be accessed anymore. This check also
requires memory ordering, which is not provided when the first lookup
fails. To achieve that the check is preceeded by a smp_rmb() which pairs
with the smp_wmb() in write_seqlock() in __exit_signal(). That ensures that
the stores in posix_cpu_timers*_exit() are visible.
The history of the non-leader exec() issue goes back to the early days of
posix CPU timers, which stored a pointer to the group leader task in the
timer. That obviously fails when a non-leader exec() switches the leader.
commit e0a70217107e ("posix-cpu-timers: workaround to suppress the problems
with mt exec") added a temporary workaround for that in 2010 which survived
about 10 years. The fix for the workaround changed the task pointer to a
pid pointer, but failed to see the subtle race described above. So the
Fixes tag picks that commit, which seems to be halfways accurate.
Thanks to Frederic Weissbecker, Oleg Nesterov and Peter Zijlstra for
review, feedback and suggestions and to Wongi and Jungwoo for the excellent
bug report and analysis!
Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task")
Reported-by: Wongi Lee <qw3rtyp0@gmail.com>
Reported-by: Jungwoo Lee <jwlee2217@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
The compat version of settimeofday() uses '>' instead of '>=' when
validating tv_usec against USEC_PER_SEC, allowing the value 1000000 to pass
the check. After the subsequent conversion to nanoseconds (tv_nsec *=
NSEC_PER_USEC), this results in tv_nsec == NSEC_PER_SEC, which violates the
timespec invariant that tv_nsec must be strictly less than NSEC_PER_SEC.
The native settimeofday() was already fixed in commit ce4abda5e126 ("time:
Fix off-by-one in settimeofday() usec validation"), but the compat
counterpart was missed.
Fix it by using '>=' to reject tv_usec values outside the valid range [0,
USEC_PER_SEC - 1].
Fixes: 5e0fb1b57bea ("y2038: time: avoid timespec usage in settimeofday()")
Signed-off-by: Wang Yan <wangyan01@kylinos.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260622103348.120255-1-wangyan01@kylinos.cn
A comment in kernel/time/hrtimer.c incorrectly refers to CONFIG_NOHZ_COMMON instead of CONFIG_NO_HZ_COMMON. Correct it. Discovered while searching for CONFIG_* symbols referenced in code but not defined in any Kconfig file. Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Link: https://patch.msgid.link/20260609034314.25029-1-enelsonmoore@gmail.com
update_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with
u64 nsecs = rlim_new * NSEC_PER_SEC;
On 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC
(1000000000L) are 32-bit, so the multiplication is performed in unsigned
long and truncated for rlim_new > 4 seconds before being widened to u64.
The same file already casts to u64 for the matching computation in
check_process_timers():
u64 softns = (u64)soft * NSEC_PER_SEC;
As a result, the truncated value is installed into the CPUCLOCK_PROF
expiry cache (nextevt), causing the process CPU timer to be programmed
to fire prematurely for any RLIMIT_CPU soft limit >= 5 seconds. The
actual SIGXCPU/SIGKILL decision in check_process_timers() already casts
to u64 and is therefore correct, so limit enforcement is not broken;
only the expiry-cache programming is wrong. Apply the same cast here so
both paths convert rlim_cur identically.
64-bit kernels are unaffected.
Fixes: 858cf3a8c599 ("timers/itimer: Convert internal cputime_t units to nsec")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260616112017.1681372-1-zhanxusheng@xiaomi.com
Commit f24df84cbe05 ("time/jiffies: Register jiffies clocksource before
usage") moved the jiffies clocksource registration into
clocksource_default_clock(), so that it is registered lazily on the first
call. __clocksource_register() acquires clocksource_mutex, but the first
caller is timekeeping_init(), which invokes clocksource_default_clock()
while holding tk_core.lock, a raw spinlock.
Acquiring a sleeping mutex while holding a raw spinlock is invalid.
The default clocksource only has to be registered before
tk_setup_internals() consumes its mult/shift/maxadj. Neither
clocksource_default_clock(), the ->enable() callback, nor the registration
itself need tk_core.lock, so fetch and enable the clock before acquiring
the lock. This preserves the "register before usage" ordering while
keeping clocksource_mutex out of the raw spinlock section.
clocksource_default_clock() has a second caller,
clocksource_done_booting(), which invokes it with clocksource_mutex already
held. That path avoids a recursive lock because timekeeping_init() has
already run and set cs_jiffies_registered, so the registration is skipped
there. This change does not alter that; it only fixes the invalid wait
context in timekeeping_init().
Fixes: f24df84cbe05 ("time/jiffies: Register jiffies clocksource before usage")
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reported-by: Breno Leitao <leitao@debian.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260616070914.65818-1-mikhail.v.gavrilov@gmail.com
Pull vdso updates from Thomas Gleixner: - Remove the redundant CONFIG_GENERIC_TIME_VSYSCALL after converting the remaining users over. - Rework and sanitize the MIPS VDSO handling, so it does not handle the time related VDSO if there is no VDSO capable clocksource available. Also stop mapping VDSO data pages unconditionally even if there is no usage possible. * tag 'timers-vdso-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: MIPS: VDSO: Fold MIPS_CLOCK_VSYSCALL into MIPS_GENERIC_GETTIMEOFDAY MIPS: VDSO: Gate microMIPS restriction on GCC version MIPS: VDSO: Fold MIPS_DISABLE_VDSO into MIPS_GENERIC_GETTIMEOFDAY clocksource/drivers/mips-gic-timer: Only use VDSO_CLOCKMODE_GIC when it is a available MIPS: csrc-r4k: Only use VDSO_CLOCKMODE_R4K when it is a available MIPS: VDSO: Only map the data pages when the vDSO is used MIPS: Introduce Kconfig MIPS_GENERIC_GETTIMEOFDAY vdso/datastore: Always provide symbol declarations MAINTAINERS: Add include/linux/vdso_datastore.h to vDSO block vdso/gettimeofday: Rename __arch_get_vdso_u_timens_data() vdso/treewide: Drop GENERIC_TIME_VSYSCALL vdso/vsyscall: Gate update_vsyscall() behind CONFIG_GENERIC_GETTIMEOFDAY riscv: vdso: Drop CONFIG_GENERIC_TIME_VSYSCALL guard around syscall fallbacks
Pull timekeeping updates from Thomas Gleixner:
"Updates for NTP/timekeeping and PTP:
- Expand timekeeping snapshot mechanisms
The various snapshot functions are mostly used for PTP to collect
"atomic" snapshots of various involved clocks.
They lack support for the recently introduced AUX clocks and do not
provide the underlying counter value (e.g. TSC) to user space.
Exposing the counter value snapshot allows for better control and
steering.
Convert the hard wired ktime_get_snapshot() to take a clock ID,
which allows the caller to select the clock ID to be captured along
with CLOCK_MONONOTONIC_RAW. Additionally capture the underlying
hardware counter value and the clock source ID of the counter.
Expand the hardware based snapshot capture where devices provide a
mechanism to snapshot the hardware PTP clock and the system counter
(usually via PCI/PTM) to support AUX clocks and also provide the
captured counter value back to the caller and not only the clock
timestamps derived from it.
- Add a new optional read_snapshot() callback to clocksources
That is required to capture atomic snapshots from clocksources
which are derived from TSC with a scaling mechanism (e.g. Hyper-V,
KVMclock).
The value pair is handed back in the snapshot structure to the
callers, so they can do the necessary correlations in a more
precise way.
This touches usage sites of the affected functions and data structure
all over the tree, but stays fully backwards compatible for the
existing user space exposed interfaces. New PTP IOCTLs will provide
access to the extended functionality in later kernel versions"
* tag 'timers-ptp-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (28 commits)
ptp: vmclock: Use hw_cycles from snapshot for precise TSC pairing
x86/kvmclock: Implement read_snapshot() for kvmclock clocksource
clocksource/hyperv: Implement read_snapshot() for TSC page clocksource
timekeeping: Add clocksource read_snapshot() method and hw_cycles to snapshot
ptp: Switch to ktime_get_snapshot_id() for pre/post timestamps
timekeeping: Add support for AUX clock cross timestamping
timekeeping: Remove system_device_crosststamp::sys_realtime
ALSA: hda/common: Use system_device_crosststamp::sys_systime
wifi: iwlwifi: Use system_device_crosststamp::sys_systime
ptp: Use system_device_crosststamp::sys_systime
timekeeping: Prepare for cross timestamps on arbitrary clock IDs
timekeeping: Remove ktime_get_snapshot()
virtio_rtc: Use provided clock ID for history snapshot
net/mlx5: Use provided clock ID for history snapshot
igc: Use provided clock ID for history snapshot
ice/ptp: Use provided clock ID for history snapshot
wifi: iwlwifi: Adopt PTP cross timestamps to core changes
timekeeping: Add CLOCK ID to system_device_crosststamp
timekeeping: Add system_counterval_t to struct system_device_crosststamp
timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()
...