[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 38.712190] audit: type=1800 audit(1549066372.604:25): pid=7647 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 38.733286] audit: type=1800 audit(1549066372.604:26): pid=7647 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 38.753396] audit: type=1800 audit(1549066372.604:27): pid=7647 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.39' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 63.568943] [ 63.570769] ===================================================== [ 63.576981] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [ 63.583871] 5.0.0-rc4+ #56 Not tainted [ 63.587743] ----------------------------------------------------- [ 63.593968] syz-executor263/8874 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 63.601306] 00000000c469f622 (&ctx->fd_wqh){....}, at: io_submit_one+0xedf/0x1cf0 [ 63.608977] [ 63.608977] and this task is already holding: [ 63.614942] 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 [ 63.623609] which would create a new lock dependency: [ 63.628771] (&(&ctx->ctx_lock)->rlock){..-.} -> (&ctx->fd_wqh){....} [ 63.635335] [ 63.635335] but this new dependency connects a SOFTIRQ-irq-safe lock: [ 63.643364] (&(&ctx->ctx_lock)->rlock){..-.} [ 63.643371] [ 63.643371] ... which became SOFTIRQ-irq-safe at: [ 63.654162] lock_acquire+0x16f/0x3f0 [ 63.658033] _raw_spin_lock_irq+0x60/0x80 [ 63.662251] free_ioctx_users+0x2d/0x4a0 [ 63.666381] percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 [ 63.671900] rcu_process_callbacks+0x928/0x1390 [ 63.676649] __do_softirq+0x266/0x95a [ 63.680577] irq_exit+0x180/0x1d0 [ 63.684118] smp_apic_timer_interrupt+0x14a/0x570 [ 63.689030] apic_timer_interrupt+0xf/0x20 [ 63.693336] native_safe_halt+0x2/0x10 [ 63.697293] arch_cpu_idle+0x10/0x20 [ 63.701076] default_idle_call+0x36/0x90 [ 63.705209] do_idle+0x386/0x570 [ 63.708643] cpu_startup_entry+0x1b/0x20 [ 63.712787] rest_init+0x245/0x37b [ 63.716397] arch_call_rest_init+0xe/0x1b [ 63.720617] start_kernel+0x808/0x841 [ 63.724495] x86_64_start_reservations+0x29/0x2b [ 63.729320] x86_64_start_kernel+0x77/0x7b [ 63.733624] secondary_startup_64+0xa4/0xb0 [ 63.738006] [ 63.738006] to a SOFTIRQ-irq-unsafe lock: [ 63.743605] (&ctx->fault_pending_wqh){+.+.} [ 63.743613] [ 63.743613] ... which became SOFTIRQ-irq-unsafe at: [ 63.754512] ... [ 63.754524] lock_acquire+0x16f/0x3f0 [ 63.760318] _raw_spin_lock+0x2f/0x40 [ 63.764194] userfaultfd_release+0x497/0x6d0 [ 63.768678] __fput+0x2df/0x8d0 [ 63.772031] ____fput+0x16/0x20 [ 63.775379] task_work_run+0x14a/0x1c0 [ 63.779350] exit_to_usermode_loop+0x273/0x2c0 [ 63.784031] do_syscall_64+0x52d/0x610 [ 63.787993] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.793246] [ 63.793246] other info that might help us debug this: [ 63.793246] [ 63.801363] Chain exists of: [ 63.801363] &(&ctx->ctx_lock)->rlock --> &ctx->fd_wqh --> &ctx->fault_pending_wqh [ 63.801363] [ 63.813485] Possible interrupt unsafe locking scenario: [ 63.813485] [ 63.820395] CPU0 CPU1 [ 63.825049] ---- ---- [ 63.829690] lock(&ctx->fault_pending_wqh); [ 63.834076] local_irq_disable(); [ 63.840105] lock(&(&ctx->ctx_lock)->rlock); [ 63.847096] lock(&ctx->fd_wqh); [ 63.853043] [ 63.855776] lock(&(&ctx->ctx_lock)->rlock); [ 63.860423] [ 63.860423] *** DEADLOCK *** [ 63.860423] [ 63.866469] 1 lock held by syz-executor263/8874: [ 63.871210] #0: 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 [ 63.880352] [ 63.880352] the dependencies between SOFTIRQ-irq-safe lock and the holding lock: [ 63.889349] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 63.894174] IN-SOFTIRQ-W at: [ 63.897439] lock_acquire+0x16f/0x3f0 [ 63.902871] _raw_spin_lock_irq+0x60/0x80 [ 63.908656] free_ioctx_users+0x2d/0x4a0 [ 63.914359] percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 [ 63.925364] rcu_process_callbacks+0x928/0x1390 [ 63.931677] __do_softirq+0x266/0x95a [ 63.937113] irq_exit+0x180/0x1d0 [ 63.942203] smp_apic_timer_interrupt+0x14a/0x570 [ 63.948689] apic_timer_interrupt+0xf/0x20 [ 63.954557] native_safe_halt+0x2/0x10 [ 63.960084] arch_cpu_idle+0x10/0x20 [ 63.965434] default_idle_call+0x36/0x90 [ 63.971142] do_idle+0x386/0x570 [ 63.976202] cpu_startup_entry+0x1b/0x20 [ 63.981902] rest_init+0x245/0x37b [ 63.987073] arch_call_rest_init+0xe/0x1b [ 63.992849] start_kernel+0x808/0x841 [ 63.998277] x86_64_start_reservations+0x29/0x2b [ 64.004668] x86_64_start_kernel+0x77/0x7b [ 64.010683] secondary_startup_64+0xa4/0xb0 [ 64.016644] INITIAL USE at: [ 64.019828] lock_acquire+0x16f/0x3f0 [ 64.025178] _raw_spin_lock_irq+0x60/0x80 [ 64.030882] free_ioctx_users+0x2d/0x4a0 [ 64.036490] percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 [ 64.043495] rcu_process_callbacks+0x928/0x1390 [ 64.049776] __do_softirq+0x266/0x95a [ 64.055146] irq_exit+0x180/0x1d0 [ 64.060155] smp_apic_timer_interrupt+0x14a/0x570 [ 64.066540] apic_timer_interrupt+0xf/0x20 [ 64.072315] native_safe_halt+0x2/0x10 [ 64.077750] arch_cpu_idle+0x10/0x20 [ 64.083008] default_idle_call+0x36/0x90 [ 64.089029] do_idle+0x386/0x570 [ 64.093954] cpu_startup_entry+0x1b/0x20 [ 64.099565] start_secondary+0x404/0x5c0 [ 64.105173] secondary_startup_64+0xa4/0xb0 [ 64.111224] } [ 64.113010] ... key at: [] __key.51972+0x0/0x40 [ 64.119869] ... acquired at: [ 64.122960] lock_acquire+0x16f/0x3f0 [ 64.126916] _raw_spin_lock+0x2f/0x40 [ 64.130873] io_submit_one+0xedf/0x1cf0 [ 64.135002] __x64_sys_io_submit+0x1bd/0x580 [ 64.139567] do_syscall_64+0x103/0x610 [ 64.143614] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.148953] [ 64.150558] [ 64.150558] the dependencies between the lock to be acquired [ 64.150561] and SOFTIRQ-irq-unsafe lock: [ 64.161983] -> (&ctx->fault_pending_wqh){+.+.} { [ 64.166809] HARDIRQ-ON-W at: [ 64.170205] lock_acquire+0x16f/0x3f0 [ 64.175884] _raw_spin_lock+0x2f/0x40 [ 64.181517] userfaultfd_release+0x497/0x6d0 [ 64.187736] __fput+0x2df/0x8d0 [ 64.192822] ____fput+0x16/0x20 [ 64.197911] task_work_run+0x14a/0x1c0 [ 64.203605] exit_to_usermode_loop+0x273/0x2c0 [ 64.209994] do_syscall_64+0x52d/0x610 [ 64.215705] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.222692] SOFTIRQ-ON-W at: [ 64.226042] lock_acquire+0x16f/0x3f0 [ 64.231646] _raw_spin_lock+0x2f/0x40 [ 64.237257] userfaultfd_release+0x497/0x6d0 [ 64.243476] __fput+0x2df/0x8d0 [ 64.248572] ____fput+0x16/0x20 [ 64.253655] task_work_run+0x14a/0x1c0 [ 64.259358] exit_to_usermode_loop+0x273/0x2c0 [ 64.265750] do_syscall_64+0x52d/0x610 [ 64.271457] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.278448] INITIAL USE at: [ 64.281717] lock_acquire+0x16f/0x3f0 [ 64.287233] _raw_spin_lock+0x2f/0x40 [ 64.292755] userfaultfd_read+0x540/0x1940 [ 64.298715] __vfs_read+0x116/0x8c0 [ 64.304195] vfs_read+0x194/0x3e0 [ 64.309365] ksys_read+0xea/0x1f0 [ 64.314571] __x64_sys_read+0x73/0xb0 [ 64.320095] do_syscall_64+0x103/0x610 [ 64.325713] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.332616] } [ 64.334498] ... key at: [] __key.44851+0x0/0x40 [ 64.341317] ... acquired at: [ 64.344494] _raw_spin_lock+0x2f/0x40 [ 64.348452] userfaultfd_read+0x540/0x1940 [ 64.352839] __vfs_read+0x116/0x8c0 [ 64.356621] vfs_read+0x194/0x3e0 [ 64.360334] ksys_read+0xea/0x1f0 [ 64.363941] __x64_sys_read+0x73/0xb0 [ 64.367903] do_syscall_64+0x103/0x610 [ 64.371948] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.377285] [ 64.378900] -> (&ctx->fd_wqh){....} { [ 64.382707] INITIAL USE at: [ 64.385890] lock_acquire+0x16f/0x3f0 [ 64.391252] _raw_spin_lock_irq+0x60/0x80 [ 64.396947] userfaultfd_read+0x27a/0x1940 [ 64.402730] __vfs_read+0x116/0x8c0 [ 64.407923] vfs_read+0x194/0x3e0 [ 64.412921] ksys_read+0xea/0x1f0 [ 64.417918] __x64_sys_read+0x73/0xb0 [ 64.423267] do_syscall_64+0x103/0x610 [ 64.428717] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.435471] } [ 64.437267] ... key at: [] __key.44854+0x0/0x40 [ 64.444019] ... acquired at: [ 64.447135] lock_acquire+0x16f/0x3f0 [ 64.451092] _raw_spin_lock+0x2f/0x40 [ 64.455049] io_submit_one+0xedf/0x1cf0 [ 64.459179] __x64_sys_io_submit+0x1bd/0x580 [ 64.463745] do_syscall_64+0x103/0x610 [ 64.467788] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.473124] [ 64.474729] [ 64.474729] stack backtrace: [ 64.479329] CPU: 1 PID: 8874 Comm: syz-executor263 Not tainted 5.0.0-rc4+ #56 [ 64.486580] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 64.495913] Call Trace: [ 64.498493] dump_stack+0x172/0x1f0 [ 64.502120] check_usage.cold+0x60f/0x940 [ 64.506259] ? check_usage_forwards+0x340/0x340 [ 64.511018] ? __kernel_text_address+0xd/0x40 [ 64.515500] ? check_noncircular+0x20/0x20 [ 64.519742] ? save_trace+0x290/0x290 [ 64.523525] __lock_acquire+0x1f47/0x4700 [ 64.527656] ? __lock_acquire+0x1f47/0x4700 [ 64.532090] ? mark_held_locks+0x100/0x100 [ 64.536307] ? __debug_object_init+0x190/0xc30 [ 64.540871] ? mark_held_locks+0x100/0x100 [ 64.545087] ? add_wait_queue+0x112/0x170 [ 64.549219] ? _raw_spin_unlock_irqrestore+0x6b/0xe0 [ 64.554303] ? add_wait_queue+0x112/0x170 [ 64.558433] ? lockdep_hardirqs_on+0x415/0x5d0 [ 64.563114] ? trace_hardirqs_on+0x67/0x230 [ 64.567421] ? kasan_check_read+0x11/0x20 [ 64.571552] lock_acquire+0x16f/0x3f0 [ 64.575342] ? io_submit_one+0xedf/0x1cf0 [ 64.579483] _raw_spin_lock+0x2f/0x40 [ 64.583269] ? io_submit_one+0xedf/0x1cf0 [ 64.587408] io_submit_one+0xedf/0x1cf0 [ 64.591384] ? init_once_userfaultfd_ctx+0xd0/0xd0 [ 64.596302] ? ioctx_alloc+0x1db0/0x1db0 [ 64.600345] ? __might_fault+0x12b/0x1e0 [ 64.604388] ? aio_setup_rw+0x180/0x180 [ 64.608349] __x64_sys_io_submit+0x1bd/0x580 [ 64.612741] ? __x64_sys_io_submit+0x1bd/0x580 [ 64.617306] ? __ia32_sys_io_destroy+0x420/0x420 [ 64.622049] ? kasan_check_read+0x11/0x20 [