random: sshd: uninitialized urandom read (32 bytes read) audit: type=1400 audit(1555360046.272:36): avc: denied { map } for pid=7096 comm="syz-executor178" path="/root/syz-executor178930288" dev="sda1" ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 ====================================================== WARNING: possible circular locking dependency detected 4.14.111 #1 Not tainted ------------------------------------------------------ syz-executor178/7102 is trying to acquire lock: (event_mutex){+.+.}, at: [] perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 but task is already holding lock: (&event->child_mutex){+.+.}, at: [] perf_event_release_kernel+0x207/0x7a0 kernel/events/core.c:4397 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&event->child_mutex){+.+.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_read_value+0x7a/0x410 kernel/events/core.c:4447 perf_read_one kernel/events/core.c:4569 [inline] __perf_read kernel/events/core.c:4620 [inline] perf_read+0x407/0x810 kernel/events/core.c:4633 __vfs_read+0x107/0x6b0 fs/read_write.c:411 vfs_read+0x137/0x350 fs/read_write.c:447 SYSC_read fs/read_write.c:573 [inline] SyS_read+0xb8/0x180 fs/read_write.c:566 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #4 (&cpuctx_mutex){+.+.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_init_cpu+0xc2/0x170 kernel/events/core.c:11221 perf_event_init+0x2d8/0x31a kernel/events/core.c:11268 start_kernel+0x3b9/0x700 init/main.c:621 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:380 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:361 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #3 (pmus_lock){+.+.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_event_init_cpu+0x2f/0x170 kernel/events/core.c:11215 cpuhp_invoke_callback+0x1ec/0x1ac0 kernel/cpu.c:184 cpuhp_up_callbacks kernel/cpu.c:572 [inline] _cpu_up+0x228/0x530 kernel/cpu.c:1134 do_cpu_up+0x121/0x150 kernel/cpu.c:1169 cpu_up+0x1b/0x20 kernel/cpu.c:1177 smp_init+0x157/0x173 kernel/smp.c:578 kernel_init_freeable+0x30e/0x538 init/main.c:1067 kernel_init+0x12/0x162 init/main.c:999 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 -> #2 (cpu_hotplug_lock.rw_sem){++++}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 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+0x3d/0xc0 kernel/cpu.c:295 static_key_slow_inc+0x13/0x30 kernel/jump_label.c:123 tracepoint_add_func kernel/tracepoint.c:223 [inline] tracepoint_probe_register_prio+0x4dc/0x6d0 kernel/tracepoint.c:283 tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304 trace_event_reg+0x277/0x330 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+0x450/0xaa0 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8104 perf_try_init_event+0x170/0x210 kernel/events/core.c:9340 perf_init_event kernel/events/core.c:9378 [inline] perf_event_alloc.part.0+0xd48/0x2540 kernel/events/core.c:9638 perf_event_alloc kernel/events/core.c:9991 [inline] SYSC_perf_event_open+0xa2d/0x24c0 kernel/events/core.c:10095 SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9981 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #1 (tracepoints_mutex){+.+.}: lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 tracepoint_probe_register_prio+0x36/0x6d0 kernel/tracepoint.c:279 tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304 trace_event_reg+0x277/0x330 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+0x450/0xaa0 kernel/trace/trace_event_perf.c:221 perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8104 perf_try_init_event+0x170/0x210 kernel/events/core.c:9340 perf_init_event kernel/events/core.c:9378 [inline] perf_event_alloc.part.0+0xd48/0x2540 kernel/events/core.c:9638 perf_event_alloc kernel/events/core.c:9991 [inline] SYSC_perf_event_open+0xa2d/0x24c0 kernel/events/core.c:10095 SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9981 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (event_mutex){+.+.}: check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 tp_perf_event_destroy+0x16/0x20 kernel/events/core.c:8088 _free_event+0x332/0xe70 kernel/events/core.c:4238 free_event+0x38/0x50 kernel/events/core.c:4265 perf_event_release_kernel+0x364/0x7a0 kernel/events/core.c:4409 perf_release+0x37/0x50 kernel/events/core.c:4435 __fput+0x277/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x119/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x7df/0x2c10 kernel/exit.c:874 do_group_exit+0x111/0x330 kernel/exit.c:977 get_signal+0x348/0x1a80 kernel/signal.c:2407 do_signal+0x86/0x1980 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x15c/0x220 arch/x86/entry/common.c:159 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:267 [inline] do_syscall_64+0x4a9/0x630 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x42/0xb7 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-executor178/7102: #0: (&ctx->mutex){+.+.}, at: [] perf_event_release_kernel+0x1fd/0x7a0 kernel/events/core.c:4396 #1: (&event->child_mutex){+.+.}, at: [] perf_event_release_kernel+0x207/0x7a0 kernel/events/core.c:4397 stack backtrace: CPU: 0 PID: 7102 Comm: syz-executor178 Not tainted 4.14.111 #1 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+0x138/0x19c lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234 tp_perf_event_destroy+0x16/0x20 kernel/events/core.c:8088 _free_event+0x332/0xe70 kernel/events/core.c:4238 free_event+0x38/0x50 kernel/events/core.c:4265 perf_event_release_kernel+0x364/0x7a0 kernel/events/core.c:4409 perf_release+0x37/0x50 kernel/events/core.c:4435 __fput+0x277/0x7a0 fs/file_table.c:210 ____fput+0x16/0x20 fs/file_table.c:244 task_work_run+0x119/0x190 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x7df/0x2c10 kernel/exit.c:874 do_group_exit+0x111/0x330 kernel/exit.c:977 get_signal+0x348/0x1a80 kernel/signal.c:2407 do_signal+0x86/0x1980 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x15c/0x220 arch/x86/entry/common.c:159 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:267 [inline] do_syscall_64+0x4a9/0x630 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4468d9 RSP: 002b:00007f7ff2acbdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00000000006dbc38 RCX: 00000000004468d9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc38 RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c R13: 00007ffe1990481f R14: 00007f7ff2acc9c0 R15: 20c49ba5e353f7cf