linux/kernel/time, branch v5.5

tick/sched: Annotate lockless access to last_jiffies_update

2020-01-15T09:54:12Z

syzbot (KCSAN) reported a data-race in tick_do_update_jiffies64(): BUG: KCSAN: data-race in tick_do_update_jiffies64 / tick_do_update_jiffies64 write to 0xffffffff8603d008 of 8 bytes by interrupt on cpu 1: tick_do_update_jiffies64+0x100/0x250 kernel/time/tick-sched.c:73 tick_sched_do_timer+0xd4/0xe0 kernel/time/tick-sched.c:138 tick_sched_timer+0x43/0xe0 kernel/time/tick-sched.c:1292 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x274/0x5f0 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 arch_local_irq_restore arch/x86/include/asm/paravirt.h:756 [inline] kcsan_setup_watchpoint+0x1d4/0x460 kernel/kcsan/core.c:436 check_access kernel/kcsan/core.c:466 [inline] __tsan_read1 kernel/kcsan/core.c:593 [inline] __tsan_read1+0xc2/0x100 kernel/kcsan/core.c:593 kallsyms_expand_symbol.constprop.0+0x70/0x160 kernel/kallsyms.c:79 kallsyms_lookup_name+0x7f/0x120 kernel/kallsyms.c:170 insert_report_filterlist kernel/kcsan/debugfs.c:155 [inline] debugfs_write+0x14b/0x2d0 kernel/kcsan/debugfs.c:256 full_proxy_write+0xbd/0x100 fs/debugfs/file.c:225 __vfs_write+0x67/0xc0 fs/read_write.c:494 vfs_write fs/read_write.c:558 [inline] vfs_write+0x18a/0x390 fs/read_write.c:542 ksys_write+0xd5/0x1b0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x4c/0x60 fs/read_write.c:620 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffffffff8603d008 of 8 bytes by task 0 on cpu 0: tick_do_update_jiffies64+0x2b/0x250 kernel/time/tick-sched.c:62 tick_nohz_update_jiffies kernel/time/tick-sched.c:505 [inline] tick_nohz_irq_enter kernel/time/tick-sched.c:1257 [inline] tick_irq_enter+0x139/0x1c0 kernel/time/tick-sched.c:1274 irq_enter+0x4f/0x60 kernel/softirq.c:354 entering_irq arch/x86/include/asm/apic.h:517 [inline] entering_ack_irq arch/x86/include/asm/apic.h:523 [inline] smp_apic_timer_interrupt+0x55/0x280 arch/x86/kernel/apic/apic.c:1133 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x1af/0x280 kernel/sched/idle.c:263 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:355 rest_init+0xec/0xf6 init/main.c:452 arch_call_rest_init+0x17/0x37 start_kernel+0x838/0x85e init/main.c:786 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x72/0x76 arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc7+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Use READ_ONCE() and WRITE_ONCE() to annotate this expected race. Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20191205045619.204946-1-edumazet@google.com

time/posix-stubs: Provide compat itimer supoprt for alpha

2020-01-09T17:20:23Z

Using compat_sys_getitimer and compat_sys_setitimer on alpha causes a link failure in the Alpha tinyconfig and other configurations that turn off CONFIG_POSIX_TIMERS. Use the same #ifdef check for the stub version as well. Fixes: 4c22ea2b9120 ("y2038: use compat_{get,set}_itimer on alpha") Reported-by: Guenter Roeck Reported-by: kbuild test robot Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Link: https://lore.kernel.org/r/20191207191043.656328-1-arnd@arndb.de

ptp: fix the race between the release of ptp_clock and cdev

2019-12-31T04:19:27Z

In a case when a ptp chardev (like /dev/ptp0) is open but an underlying device is removed, closing this file leads to a race. This reproduces easily in a kvm virtual machine: ts# cat openptp0.c int main() { ... fp = fopen("/dev/ptp0", "r"); ... sleep(10); } ts# uname -r 5.5.0-rc3-46cf053e ts# cat /proc/cmdline ... slub_debug=FZP ts# modprobe ptp_kvm ts# ./openptp0 & [1] 670 opened /dev/ptp0, sleeping 10s... ts# rmmod ptp_kvm ts# ls /dev/ptp* ls: cannot access '/dev/ptp*': No such file or directory ts# ...woken up [ 48.010809] general protection fault: 0000 [#1] SMP [ 48.012502] CPU: 6 PID: 658 Comm: openptp0 Not tainted 5.5.0-rc3-46cf053e #25 [ 48.014624] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ... [ 48.016270] RIP: 0010:module_put.part.0+0x7/0x80 [ 48.017939] RSP: 0018:ffffb3850073be00 EFLAGS: 00010202 [ 48.018339] RAX: 000000006b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: ffff89a476c00ad0 [ 48.018936] RDX: fffff65a08d3ea08 RSI: 0000000000000247 RDI: 6b6b6b6b6b6b6b6b [ 48.019470] ... ^^^ a slub poison [ 48.023854] Call Trace: [ 48.024050] __fput+0x21f/0x240 [ 48.024288] task_work_run+0x79/0x90 [ 48.024555] do_exit+0x2af/0xab0 [ 48.024799] ? vfs_write+0x16a/0x190 [ 48.025082] do_group_exit+0x35/0x90 [ 48.025387] __x64_sys_exit_group+0xf/0x10 [ 48.025737] do_syscall_64+0x3d/0x130 [ 48.026056] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 48.026479] RIP: 0033:0x7f53b12082f6 [ 48.026792] ... [ 48.030945] Modules linked in: ptp i6300esb watchdog [last unloaded: ptp_kvm] [ 48.045001] Fixing recursive fault but reboot is needed! This happens in: static void __fput(struct file *file) { ... if (file->f_op->release) file->f_op->release(inode, file); <<< cdev is kfree'd here if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL && !(mode & FMODE_PATH))) { cdev_put(inode->i_cdev); <<< cdev fields are accessed here Namely: __fput() posix_clock_release() kref_put(&clk->kref, delete_clock) <<< the last reference delete_clock() delete_ptp_clock() kfree(ptp) <<< cdev is embedded in ptp cdev_put module_put(p->owner) <<< *p is kfree'd, bang! Here cdev is embedded in posix_clock which is embedded in ptp_clock. The race happens because ptp_clock's lifetime is controlled by two refcounts: kref and cdev.kobj in posix_clock. This is wrong. Make ptp_clock's sysfs device a parent of cdev with cdev_device_add() created especially for such cases. This way the parent device with its ptp_clock is not released until all references to the cdev are released. This adds a requirement that an initialized but not exposed struct device should be provided to posix_clock_register() by a caller instead of a simple dev_t. This approach was adopted from the commit 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev"). See details of the implementation in the commit 233ed09d7fda ("chardev: add helper function to register char devs with a struct device"). Link: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u Analyzed-by: Stephen Johnston Analyzed-by: Vern Lovejoy Signed-off-by: Vladis Dronov Acked-by: Richard Cochran Signed-off-by: David S. Miller

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-12-03T20:20:25Z

Pull timer updates from Ingo Molnar: "The main changes in the timer code in this cycle were: - Clockevent updates: - timer-of framework cleanups. (Geert Uytterhoeven) - Use timer-of for the renesas-ostm and the device name to prevent name collision in case of multiple timers. (Geert Uytterhoeven) - Check if there is an error after calling of_clk_get in asm9260 (Chuhong Yuan) - ABI fix: Zero out high order bits of nanoseconds on compat syscalls. This got broken a year ago, with apparently no side effects so far. Since the kernel would use random data otherwise I don't think we'd have other options but to fix the bug, even if there was a side effect to applications (Dmitry Safonov) - Optimize ns_to_timespec64() on 32-bit systems: move away from div_s64_rem() which can be slow, to div_u64_rem() which is faster (Arnd Bergmann) - Annotate KCSAN-reported false positive data races in hrtimer_is_queued() users by moving timer->state handling over to the READ_ONCE()/WRITE_ONCE() APIs. This documents these accesses (Eric Dumazet) - Misc cleanups and small fixes" [ I undid the "ABI fix" and updated the comments instead. The reason there were apparently no side effects is that the fix was a no-op. The updated comment is to say _why_ it was a no-op. - Linus ] * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: time: Zero the upper 32-bits in __kernel_timespec on 32-bit time: Rename tsk->real_start_time to ->start_boottime hrtimer: Remove the comment about not used HRTIMER_SOFTIRQ time: Fix spelling mistake in comment time: Optimize ns_to_timespec64() hrtimer: Annotate lockless access to timer->state clocksource/drivers/asm9260: Add a check for of_clk_get clocksource/drivers/renesas-ostm: Use unique device name instead of ostm clocksource/drivers/renesas-ostm: Convert to timer_of clocksource/drivers/timer-of: Use unique device name instead of timer clocksource/drivers/timer-of: Convert last full_name to %pOF

Merge tag 'y2038-cleanups-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground

2019-12-01T22:00:59Z

Pull y2038 cleanups from Arnd Bergmann: "y2038 syscall implementation cleanups This is a series of cleanups for the y2038 work, mostly intended for namespace cleaning: the kernel defines the traditional time_t, timeval and timespec types that often lead to y2038-unsafe code. Even though the unsafe usage is mostly gone from the kernel, having the types and associated functions around means that we can still grow new users, and that we may be missing conversions to safe types that actually matter. There are still a number of driver specific patches needed to get the last users of these types removed, those have been submitted to the respective maintainers" Link: https://lore.kernel.org/lkml/20191108210236.1296047-1-arnd@arndb.de/ * tag 'y2038-cleanups-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (26 commits) y2038: alarm: fix half-second cut-off y2038: ipc: fix x32 ABI breakage y2038: fix typo in powerpc vdso "LOPART" y2038: allow disabling time32 system calls y2038: itimer: change implementation to timespec64 y2038: move itimer reset into itimer.c y2038: use compat_{get,set}_itimer on alpha y2038: itimer: compat handling to itimer.c y2038: time: avoid timespec usage in settimeofday() y2038: timerfd: Use timespec64 internally y2038: elfcore: Use __kernel_old_timeval for process times y2038: make ns_to_compat_timeval use __kernel_old_timeval y2038: socket: use __kernel_old_timespec instead of timespec y2038: socket: remove timespec reference in timestamping y2038: syscalls: change remaining timeval to __kernel_old_timeval y2038: rusage: use __kernel_old_timeval y2038: uapi: change __kernel_time_t to __kernel_old_time_t y2038: stat: avoid 'time_t' in 'struct stat' y2038: ipc: remove __kernel_time_t reference from headers y2038: vdso: powerpc: avoid timespec references ...

Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-11-26T23:42:43Z

Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - Dynamic tick (nohz) updates, perhaps most notably changes to force the tick on when needed due to lengthy in-kernel execution on CPUs on which RCU is waiting. - Linux-kernel memory consistency model updates. - Replace rcu_swap_protected() with rcu_prepace_pointer(). - Torture-test updates. - Documentation updates. - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits) security/safesetid: Replace rcu_swap_protected() with rcu_replace_pointer() net/sched: Replace rcu_swap_protected() with rcu_replace_pointer() net/netfilter: Replace rcu_swap_protected() with rcu_replace_pointer() net/core: Replace rcu_swap_protected() with rcu_replace_pointer() bpf/cgroup: Replace rcu_swap_protected() with rcu_replace_pointer() fs/afs: Replace rcu_swap_protected() with rcu_replace_pointer() drivers/scsi: Replace rcu_swap_protected() with rcu_replace_pointer() drm/i915: Replace rcu_swap_protected() with rcu_replace_pointer() x86/kvm/pmu: Replace rcu_swap_protected() with rcu_replace_pointer() rcu: Upgrade rcu_swap_protected() to rcu_replace_pointer() rcu: Suppress levelspread uninitialized messages rcu: Fix uninitialized variable in nocb_gp_wait() rcu: Update descriptions for rcu_future_grace_period tracepoint rcu: Update descriptions for rcu_nocb_wake tracepoint rcu: Remove obsolete descriptions for rcu_barrier tracepoint rcu: Ensure that ->rcu_urgent_qs is set before resched IPI workqueue: Convert for_each_wq to use built-in list check rcu: Several rcu_segcblist functions can be static rcu: Remove unused function hlist_bl_del_init_rcu() Documentation: Rename rcu_node_context_switch() to rcu_note_context_switch() ...

y2038: alarm: fix half-second cut-off

2019-11-25T20:52:35Z

Changing alarm_itimer accidentally broke the logic for arithmetic rounding of half seconds in the return code. Change it to a constant based on NSEC_PER_SEC, as suggested by Ben Hutchings. Fixes: bd40a175769d ("y2038: itimer: change implementation to timespec64") Reported-by: Ben Hutchings Signed-off-by: Arnd Bergmann

Merge branch 'timers/urgent' into timers/core, to pick up fix

2019-11-25T14:43:15Z

Signed-off-by: Ingo Molnar

time: Zero the upper 32-bits in __kernel_timespec on 32-bit

2019-11-21T00:17:58Z

On compat interfaces, the high order bits of nanoseconds should be zeroed out. This is because the application code or the libc do not guarantee zeroing of these. If used without zeroing, kernel might be at risk of using timespec values incorrectly. Originally it was handled correctly, but lost during is_compat_syscall() cleanup. Revert the condition back to check CONFIG_64BIT. Fixes: 98f76206b335 ("compat: Cleanup in_compat_syscall() callers") Reported-by: Ben Hutchings Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20191121000303.126523-1-dima@arista.com

Merge tag 'v5.4-rc8' into sched/core, to pick up fixes and dependencies

2019-11-18T13:41:02Z

Signed-off-by: Ingo Molnar