syzbot

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BUG: KCSAN: data-race in __perf_event_overflow / __perf_event_set_bpf_prog

write to 0xffff88811ca93dc8 of 8 bytes by task 5567 on cpu 0:
 perf_event_set_bpf_handler kernel/events/core.c:10644 [inline]
 __perf_event_set_bpf_prog+0x419/0x470 kernel/events/core.c:11595
 _perf_ioctl kernel/events/core.c:6665 [inline]
 perf_ioctl+0x92e/0x15d0 kernel/events/core.c:6725
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811ca93dc8 of 8 bytes by interrupt on cpu 1:
 __perf_event_overflow+0x252/0x920 kernel/events/core.c:10702
 perf_swevent_hrtimer+0x28d/0x310 kernel/events/core.c:12157
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x207/0x4c0 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x269/0x810 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 kcsan_setup_watchpoint+0x404/0x410 kernel/kcsan/core.c:705
 strlen+0x19/0x40 lib/string.c:420
 __fortify_strlen include/linux/fortify-string.h:266 [inline]
 insert_entry fs/proc/proc_sysctl.c:167 [inline]
 insert_header+0x694/0x970 fs/proc/proc_sysctl.c:252
 __register_sysctl_table+0xb69/0xc00 fs/proc/proc_sysctl.c:1399
 register_net_sysctl_sz+0x19f/0x1c0 net/sysctl_net.c:171
 __addrconf_sysctl_register+0x240/0x340 net/ipv6/addrconf.c:7323
 addrconf_sysctl_register+0xe6/0x130 net/ipv6/addrconf.c:7371
 ipv6_add_dev+0x8a2/0xac0 net/ipv6/addrconf.c:460
 addrconf_notify+0x4a5/0x8f0 net/ipv6/addrconf.c:3650
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info net/core/dev.c:2243 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
 call_netdevice_notifiers+0xb5/0x110 net/core/dev.c:2295
 register_netdevice+0xe24/0x1000 net/core/dev.c:11444
 ppp_unit_register drivers/net/ppp/ppp_generic.c:1219 [inline]
 ppp_dev_configure+0x623/0x6e0 drivers/net/ppp/ppp_generic.c:1280
 ppp_create_interface drivers/net/ppp/ppp_generic.c:3374 [inline]
 ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1065 [inline]
 ppp_ioctl+0x52f/0x1230 drivers/net/ppp/ppp_generic.c:738
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffffc9001227f000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5549 Comm: syz.5.559 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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