wireguard-linux/kernel/time, branch jd/bump-compilers

timekeeping: Fix bogus clock_was_set() invocation in do_adjtimex()

2024-08-05T14:14:14Z

The addition of the bases argument to clock_was_set() fixed up all call sites correctly except for do_adjtimex(). This uses CLOCK_REALTIME instead of CLOCK_SET_WALL as argument. CLOCK_REALTIME is 0. As a result the effect of that clock_was_set() notification is incomplete and might result in timers expiring late because the hrtimer code does not re-evaluate the affected clock bases. Use CLOCK_SET_WALL instead of CLOCK_REALTIME to tell the hrtimers code which clock bases need to be re-evaluated. Fixes: 17a1b8826b45 ("hrtimer: Add bases argument to clock_was_set()") Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/877ccx7igo.ffs@tglx

ntp: Safeguard against time_constant overflow

2024-08-05T14:14:14Z

Using syzkaller with the recently reintroduced signed integer overflow sanitizer produces this UBSAN report: UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:738:18 9223372036854775806 + 4 cannot be represented in type 'long' Call Trace: handle_overflow+0x171/0x1b0 __do_adjtimex+0x1236/0x1440 do_adjtimex+0x2be/0x740 The user supplied time_constant value is incremented by four and then clamped to the operating range. Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user supplied value was sanity checked to be in the operating range. That change removed the sanity check and relied on clamping after incrementing which does not work correctly when the user supplied value is in the overflow zone of the '+ 4' operation. The operation requires CAP_SYS_TIME and the side effect of the overflow is NTP getting out of sync. Similar to the fixups for time_maxerror and time_esterror, clamp the user space supplied value to the operating range. [ tglx: Switch to clamping ] Fixes: eea83d896e31 ("ntp: NTP4 user space bits update") Signed-off-by: Justin Stitt Signed-off-by: Thomas Gleixner Cc: Miroslav Lichvar Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-c-v2-1-f3a80096f36f@google.com Closes: https://github.com/KSPP/linux/issues/352

ntp: Clamp maxerror and esterror to operating range

2024-08-05T14:14:14Z

Using syzkaller alongside the newly reintroduced signed integer overflow sanitizer spits out this report: UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:461:16 9223372036854775807 + 500 cannot be represented in type 'long' Call Trace: handle_overflow+0x171/0x1b0 second_overflow+0x2d6/0x500 accumulate_nsecs_to_secs+0x60/0x160 timekeeping_advance+0x1fe/0x890 update_wall_time+0x10/0x30 time_maxerror is unconditionally incremented and the result is checked against NTP_PHASE_LIMIT, but the increment itself can overflow, resulting in wrap-around to negative space. Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user supplied value was sanity checked to be in the operating range. That change removed the sanity check and relied on clamping in handle_overflow() which does not work correctly when the user supplied value is in the overflow zone of the '+ 500' operation. The operation requires CAP_SYS_TIME and the side effect of the overflow is NTP getting out of sync. Miroslav confirmed that the input value should be clamped to the operating range and the same applies to time_esterror. The latter is not used by the kernel, but the value still should be in the operating range as it was before the sanity check got removed. Clamp them to the operating range. [ tglx: Changed it to clamping and included time_esterror ] Fixes: eea83d896e31 ("ntp: NTP4 user space bits update") Signed-off-by: Justin Stitt Signed-off-by: Thomas Gleixner Cc: Miroslav Lichvar Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-usec-v2-1-d539180f2b79@google.com Closes: https://github.com/KSPP/linux/issues/354

clocksource: Fix brown-bag boolean thinko in cs_watchdog_read()

2024-08-02T16:29:28Z

The current "nretries > 1 || nretries >= max_retries" check in cs_watchdog_read() will always evaluate to true, and thus pr_warn(), if nretries is greater than 1. The intent is instead to never warn on the first try, but otherwise warn if the successful retry was the last retry. Therefore, change that "||" to "&&". Fixes: db3a34e17433 ("clocksource: Retry clock read if long delays detected") Reported-by: Borislav Petkov Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240802154618.4149953-2-paulmck@kernel.org

tick/broadcast: Move per CPU pointer access into the atomic section

2024-07-31T10:37:43Z

The recent fix for making the take over of the broadcast timer more reliable retrieves a per CPU pointer in preemptible context. This went unnoticed as compilers hoist the access into the non-preemptible region where the pointer is actually used. But of course it's valid that the compiler keeps it at the place where the code puts it which rightfully triggers: BUG: using smp_processor_id() in preemptible [00000000] code: caller is hotplug_cpu__broadcast_tick_pull+0x1c/0xc0 Move it to the actual usage site which is in a non-preemptible region. Fixes: f7d43dd206e7 ("tick/broadcast: Make takeover of broadcast hrtimer reliable") Reported-by: David Wang <00107082@163.com> Signed-off-by: Thomas Gleixner Tested-by: Yu Liao Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/87ttg56ers.ffs@tglx

Merge tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-07-27T17:19:55Z

Pull timer migration updates from Thomas Gleixner: "Fixes and minor updates for the timer migration code: - Stop testing the group->parent pointer as it is not guaranteed to be stable over a chain of operations by design. This includes a warning which would be nice to have but it produces false positives due to the racy nature of the check. - Plug a race between CPUs going in and out of idle and a CPU hotplug operation. The latter can create and connect a new hierarchy level which is missed in the concurrent updates of CPUs which go into idle. As a result the events of such a CPU might not be processed and timers go stale. Cure it by splitting the hotplug operation into a prepare and online callback. The prepare callback is guaranteed to run on an online and therefore active CPU. This CPU updates the hierarchy and being online ensures that there is always at least one migrator active which handles the modified hierarchy correctly when going idle. The online callback which runs on the incoming CPU then just marks the CPU active and brings it into operation. - Improve tracing and polish the code further so it is more obvious what's going on" * tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timers/migration: Fix grammar in comment timers/migration: Spare write when nothing changed timers/migration: Rename childmask by groupmask to make naming more obvious timers/migration: Read childmask and parent pointer in a single place timers/migration: Use a single struct for hierarchy walk data timers/migration: Improve tracing timers/migration: Move hierarchy setup into cpuhotplug prepare callback timers/migration: Do not rely always on group->parent

sysctl: treewide: constify the ctl_table argument of proc_handlers

2024-07-24T18:59:29Z

const qualify the struct ctl_table argument in the proc_handler function signatures. This is a prerequisite to moving the static ctl_table structs into .rodata data which will ensure that proc_handler function pointers cannot be modified. This patch has been generated by the following coccinelle script: ``` virtual patch @r1@ identifier ctl, write, buffer, lenp, ppos; identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)"; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos); @r2@ identifier func, ctl, write, buffer, lenp, ppos; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos) { ... } @r3@ identifier func; @@ int func( - struct ctl_table * + const struct ctl_table * ,int , void *, size_t *, loff_t *); @r4@ identifier func, ctl; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int , void *, size_t *, loff_t *); @r5@ identifier func, write, buffer, lenp, ppos; @@ int func( - struct ctl_table * + const struct ctl_table * ,int write, void *buffer, size_t *lenp, loff_t *ppos); ``` * Code formatting was adjusted in xfs_sysctl.c to comply with code conventions. The xfs_stats_clear_proc_handler, xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where adjusted. * The ctl_table argument in proc_watchdog_common was const qualified. This is called from a proc_handler itself and is calling back into another proc_handler, making it necessary to change it as part of the proc_handler migration. Co-developed-by: Thomas Weißschuh Signed-off-by: Thomas Weißschuh Co-developed-by: Joel Granados Signed-off-by: Joel Granados

timers/migration: Fix grammar in comment

2024-07-22T16:03:34Z

Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20240716-tmigr-fixes-v4-8-757baa7803fe@linutronix.de

timers/migration: Spare write when nothing changed

2024-07-22T16:03:34Z

The wakeup value is written unconditionally in tmigr_cpu_new_timer(). When there was no new next timer expiry that needs to be propagated, then the value that was read before is written. This is not required. Move the write to the place where wakeup value is changed changed. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20240716-tmigr-fixes-v4-7-757baa7803fe@linutronix.de

timers/migration: Rename childmask by groupmask to make naming more obvious

2024-07-22T16:03:34Z

childmask in the group reflects the mask that is required to 'reference' this group in the parent. When reading childmask, this might be confusing, as this suggests, that this is the mask of the child of the group. Clarify this by renaming childmask in the tmigr_group and tmc_group by groupmask. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20240716-tmigr-fixes-v4-6-757baa7803fe@linutronix.de