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KCSAN: data-race in collect_posix_cputimers / run_posix_cpu_timers (2)

Status: moderation: reported on 2024/06/20 00:03
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+2224b81350eb7e28cf93@syzkaller.appspotmail.com
First crash: 23d, last: 23d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in collect_posix_cputimers / run_posix_cpu_timers kernel 1 697d 697d 0/27 auto-closed as invalid on 2022/09/19 15:12

Sample crash report:
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
==================================================================
BUG: KCSAN: data-race in collect_posix_cputimers / run_posix_cpu_timers

write to 0xffff8881046257c8 of 8 bytes by task 12096 on cpu 0:
 collect_posix_cputimers+0x4e7/0x500 kernel/time/posix-cpu-timers.c:865
 check_process_timers kernel/time/posix-cpu-timers.c:1001 [inline]
 handle_posix_cpu_timers kernel/time/posix-cpu-timers.c:1352 [inline]
 posix_cpu_timers_work+0x456/0x950 kernel/time/posix-cpu-timers.c:1169
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 get_signal+0xeee/0x1080 kernel/signal.c:2681
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881046257c8 of 8 bytes by interrupt on cpu 1:
 task_cputimers_expired kernel/time/posix-cpu-timers.c:1099 [inline]
 fastpath_timer_check kernel/time/posix-cpu-timers.c:1151 [inline]
 run_posix_cpu_timers+0x28a/0x310 kernel/time/posix-cpu-timers.c:1451
 update_process_times+0x15f/0x180 kernel/time/timer.c:2492
 tick_sched_handle kernel/time/tick-sched.c:276 [inline]
 tick_nohz_handler+0x250/0x2d0 kernel/time/tick-sched.c:297
 __run_hrtimer kernel/time/hrtimer.c:1687 [inline]
 __hrtimer_run_queues+0x20d/0x5e0 kernel/time/hrtimer.c:1751
 hrtimer_interrupt+0x210/0x7b0 kernel/time/hrtimer.c:1813
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1032 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1a0 arch/x86/kernel/apic/apic.c:1049
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

value changed: 0x0000004b8e54ab34 -> 0xffffffffffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12097 Comm: syz-executor.2 Not tainted 6.10.0-rc4-syzkaller-00052-ge5b3efbe1ab1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/20 00:02 upstream e5b3efbe1ab1 41b7e219 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in collect_posix_cputimers / run_posix_cpu_timers
* Struck through repros no longer work on HEAD.