audit: type=1400 audit(1602891681.580:8): avc: denied { execmem } for pid=6399 comm="syz-executor261" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1 ====================================================== WARNING: possible circular locking dependency detected 4.14.198-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor261/6402 is trying to acquire lock: (event_mutex){+.+.}, at: [] perf_trace_destroy+0x23/0xf0 kernel/trace/trace_event_perf.c:234 but task is already holding lock: (&event->child_mutex){+.+.}, at: [] perf_event_release_kernel+0x208/0x8a0 kernel/events/core.c:4402 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&event->child_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 perf_event_for_each_child+0x82/0x140 kernel/events/core.c:4687 _perf_ioctl+0x47f/0x1a80 kernel/events/core.c:4874 perf_ioctl+0x55/0x80 kernel/events/core.c:4886 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #4 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 perf_event_init_cpu+0xb7/0x170 kernel/events/core.c:11249 perf_event_init+0x2cc/0x308 kernel/events/core.c:11296 start_kernel+0x46a/0x770 init/main.c:620 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #3 (pmus_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 perf_event_init_cpu+0x2c/0x170 kernel/events/core.c:11243 cpuhp_invoke_callback+0x1e6/0x1a80 kernel/cpu.c:184 cpuhp_up_callbacks kernel/cpu.c:572 [inline] _cpu_up+0x219/0x500 kernel/cpu.c:1140 do_cpu_up+0x9a/0x160 kernel/cpu.c:1175 smp_init+0x197/0x1ac kernel/smp.c:578 kernel_init_freeable+0x3f4/0x619 init/main.c:1068 kernel_init+0xd/0x15b init/main.c:1000 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 -> #2 (cpu_hotplug_lock.rw_sem){++++}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] cpus_read_lock+0x39/0xc0 kernel/cpu.c:295 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:123 tracepoint_add_func+0x517/0x750 kernel/tracepoint.c:223 tracepoint_probe_register_prio kernel/tracepoint.c:283 [inline] tracepoint_probe_register+0x8c/0xc0 kernel/tracepoint.c:304 trace_event_reg+0x272/0x330 kernel/trace/trace_events.c:305 perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline] perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline] perf_trace_init+0x424/0xa30 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x79/0xf0 kernel/events/core.c:8132 perf_try_init_event+0x15b/0x1f0 kernel/events/core.c:9368 perf_init_event kernel/events/core.c:9406 [inline] perf_event_alloc.part.0+0xe2d/0x2640 kernel/events/core.c:9666 perf_event_alloc kernel/events/core.c:10019 [inline] SYSC_perf_event_open kernel/events/core.c:10123 [inline] SyS_perf_event_open+0x67f/0x24b0 kernel/events/core.c:10009 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #1 (tracepoints_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 tracepoint_probe_register_prio kernel/tracepoint.c:279 [inline] tracepoint_probe_register+0x68/0xc0 kernel/tracepoint.c:304 trace_event_reg+0x272/0x330 kernel/trace/trace_events.c:305 perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline] perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline] perf_trace_init+0x424/0xa30 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x79/0xf0 kernel/events/core.c:8132 perf_try_init_event+0x15b/0x1f0 kernel/events/core.c:9368 perf_init_event kernel/events/core.c:9406 [inline] perf_event_alloc.part.0+0xe2d/0x2640 kernel/events/core.c:9666 perf_event_alloc kernel/events/core.c:10019 [inline] SYSC_perf_event_open kernel/events/core.c:10123 [inline] SyS_perf_event_open+0x67f/0x24b0 kernel/events/core.c:10009 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (event_mutex){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 perf_trace_destroy+0x23/0xf0 kernel/trace/trace_event_perf.c:234 _free_event+0x321/0xe20 kernel/events/core.c:4243 free_event+0x32/0x40 kernel/events/core.c:4270 perf_event_release_kernel+0x368/0x8a0 kernel/events/core.c:4414 perf_release+0x33/0x40 kernel/events/core.c:4440 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xa08/0x27f0 kernel/exit.c:865 do_group_exit+0x100/0x2e0 kernel/exit.c:962 get_signal+0x38d/0x1ca0 kernel/signal.c:2423 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Chain exists of: event_mutex --> &cpuctx_mutex --> &event->child_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&event->child_mutex); lock(&cpuctx_mutex); lock(&event->child_mutex); lock(event_mutex); *** DEADLOCK *** 2 locks held by syz-executor261/6402: #0: (&ctx->mutex){+.+.}, at: [] perf_event_release_kernel+0x1fe/0x8a0 kernel/events/core.c:4401 #1: (&event->child_mutex){+.+.}, at: [] perf_event_release_kernel+0x208/0x8a0 kernel/events/core.c:4402 stack backtrace: CPU: 0 PID: 6402 Comm: syz-executor261 Not tainted 4.14.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x283 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 perf_trace_destroy+0x23/0xf0 kernel/trace/trace_event_perf.c:234 _free_event+0x321/0xe20 kernel/events/core.c:4243 free_event+0x32/0x40 kernel/events/core.c:4270 perf_event_release_kernel+0x368/0x8a0 kernel/events/core.c:4414 perf_release+0x33/0x40 kernel/events/core.c:4440 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xa08/0x27f0 kernel/exit.c:865 do_group_exit+0x100/0x2e0 kernel/exit.c:962 get_signal+0x38d/0x1ca0 kernel/signal.c:2423 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:814 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x4469b9 RSP: 002b:00007f78021c2db8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dbc38 RCX: 00000000004469b9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc38 RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c R13: 00007ffd585de21f R14: 00007f78021c39c0 R15: 20c49ba5e353f7cf