======================================================== WARNING: possible irq lock inversion dependency detected 5.6.0-syzkaller #0 Not tainted -------------------------------------------------------- systemd-udevd/4295 just changed the state of lock: ffffffff898090d8 (tasklist_lock){.+.?}-{2:2}, at: send_sigurg+0x9f/0x320 fs/fcntl.c:840 but this lock took another, SOFTIRQ-unsafe lock in the past: (&pid->wait_pidfd){+.+.}-{2:2} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pid->wait_pidfd); local_irq_disable(); lock(tasklist_lock); lock(&pid->wait_pidfd); lock(tasklist_lock); *** DEADLOCK *** 5 locks held by systemd-udevd/4295: #0: ffffffff89e3aa80 (tomoyo_ss){....}-{0:0}, at: tomoyo_path_perm+0x1ba/0x400 security/tomoyo/file.c:847 #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: __write_once_size include/linux/compiler.h:226 [inline] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: __skb_unlink include/linux/skbuff.h:2078 [inline] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: __skb_dequeue include/linux/skbuff.h:2093 [inline] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x1ad/0x7a0 net/core/dev.c:6131 #2: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: __skb_pull include/linux/skbuff.h:2309 [inline] #2: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x124/0x360 net/ipv4/ip_input.c:228 #3: ffff888051042de0 (slock-AF_INET/1){+.-.}-{2:2}, at: tcp_v4_rcv+0x2d09/0x39c0 net/ipv4/tcp_ipv4.c:1997 #4: ffff888093926b78 (&f->f_owner.lock){.+.?}-{2:2}, at: send_sigurg+0x1a/0x320 fs/fcntl.c:824 the shortest dependencies between 2nd lock and 1st lock: -> (&pid->wait_pidfd){+.+.}-{2:2} { HARDIRQ-ON-W at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:353 [inline] proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880 proc_pid_instantiate+0x51/0x150 fs/proc/base.c:3285 proc_pid_lookup+0x1da/0x340 fs/proc/base.c:3320 proc_root_lookup+0x20/0x60 fs/proc/root.c:243 __lookup_slow+0x256/0x490 fs/namei.c:1530 lookup_slow fs/namei.c:1547 [inline] walk_component+0x418/0x6a0 fs/namei.c:1846 link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166 link_path_walk fs/namei.c:2098 [inline] path_openat+0x25a/0x27d0 fs/namei.c:3342 do_filp_open+0x192/0x260 fs/namei.c:3373 do_sys_openat2+0x585/0x7d0 fs/open.c:1148 do_sys_open+0xc3/0x140 fs/open.c:1164 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 SOFTIRQ-ON-W at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:353 [inline] proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880 proc_pid_instantiate+0x51/0x150 fs/proc/base.c:3285 proc_pid_lookup+0x1da/0x340 fs/proc/base.c:3320 proc_root_lookup+0x20/0x60 fs/proc/root.c:243 __lookup_slow+0x256/0x490 fs/namei.c:1530 lookup_slow fs/namei.c:1547 [inline] walk_component+0x418/0x6a0 fs/namei.c:1846 link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166 link_path_walk fs/namei.c:2098 [inline] path_openat+0x25a/0x27d0 fs/namei.c:3342 do_filp_open+0x192/0x260 fs/namei.c:3373 do_sys_openat2+0x585/0x7d0 fs/open.c:1148 do_sys_open+0xc3/0x140 fs/open.c:1164 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 INITIAL USE at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159 __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122 do_notify_pidfd kernel/signal.c:1900 [inline] do_notify_parent+0x19e/0xe60 kernel/signal.c:1927 exit_notify kernel/exit.c:660 [inline] do_exit+0x238f/0x2dd0 kernel/exit.c:816 call_usermodehelper_exec_async+0x507/0x710 kernel/umh.c:125 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 } ... key at: [] __key.53831+0x0/0x40 ... acquired at: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159 __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122 do_notify_pidfd kernel/signal.c:1900 [inline] do_notify_parent+0x19e/0xe60 kernel/signal.c:1927 exit_notify kernel/exit.c:660 [inline] do_exit+0x238f/0x2dd0 kernel/exit.c:816 call_usermodehelper_exec_async+0x507/0x710 kernel/umh.c:125 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 -> (tasklist_lock){.+.?}-{2:2} { HARDIRQ-ON-R at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x2d/0x40 kernel/locking/spinlock.c:223 do_wait+0x3b9/0xa00 kernel/exit.c:1436 kernel_wait4+0x14c/0x260 kernel/exit.c:1611 call_usermodehelper_exec_sync kernel/umh.c:150 [inline] call_usermodehelper_exec_work+0x172/0x260 kernel/umh.c:187 process_one_work+0x965/0x16a0 kernel/workqueue.c:2266 worker_thread+0x96/0xe20 kernel/workqueue.c:2412 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 IN-SOFTIRQ-R at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x2d/0x40 kernel/locking/spinlock.c:223 send_sigurg+0x9f/0x320 fs/fcntl.c:840 sk_send_sigurg+0x76/0x300 net/core/sock.c:2855 tcp_check_urg net/ipv4/tcp_input.c:5353 [inline] tcp_urg+0x38c/0xb80 net/ipv4/tcp_input.c:5394 tcp_rcv_established+0x8f3/0x1d90 net/ipv4/tcp_input.c:5724 tcp_v4_do_rcv+0x605/0x8b0 net/ipv4/tcp_ipv4.c:1621 tcp_v4_rcv+0x2f60/0x39c0 net/ipv4/tcp_ipv4.c:2003 ip_protocol_deliver_rcu+0x57/0x880 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x220/0x360 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x1c8/0x4e0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:441 [inline] ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core+0xf5/0x160 net/core/dev.c:5187 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5301 process_backlog+0x21e/0x7a0 net/core/dev.c:6133 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x4c2/0x1070 net/core/dev.c:6639 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x192/0x1d0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:546 [inline] smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 __sanitizer_cov_trace_switch+0x32/0x70 kernel/kcov.c:309 tomoyo_domain_quota_is_ok+0x18b/0x500 security/tomoyo/util.c:1039 tomoyo_supervisor+0x2d5/0xee0 security/tomoyo/common.c:2089 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x257/0x360 security/tomoyo/file.c:573 tomoyo_path_perm+0x2f6/0x400 security/tomoyo/file.c:838 security_inode_getattr+0xeb/0x150 security/security.c:1273 vfs_getattr+0x22/0x60 fs/stat.c:117 vfs_statx+0x142/0x1e0 fs/stat.c:201 vfs_lstat include/linux/fs.h:3284 [inline] __do_sys_newlstat+0x96/0x120 fs/stat.c:364 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 SOFTIRQ-ON-R at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x2d/0x40 kernel/locking/spinlock.c:223 do_wait+0x3b9/0xa00 kernel/exit.c:1436 kernel_wait4+0x14c/0x260 kernel/exit.c:1611 call_usermodehelper_exec_sync kernel/umh.c:150 [inline] call_usermodehelper_exec_work+0x172/0x260 kernel/umh.c:187 process_one_work+0x965/0x16a0 kernel/workqueue.c:2266 worker_thread+0x96/0xe20 kernel/workqueue.c:2412 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 INITIAL USE at: lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_write_lock_irq include/linux/rwlock_api_smp.h:196 [inline] _raw_write_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:311 copy_process+0x3322/0x7110 kernel/fork.c:2206 _do_fork+0x12d/0x1010 kernel/fork.c:2430 kernel_thread+0xb8/0xf0 kernel/fork.c:2517 rest_init+0x23/0x365 init/main.c:632 start_kernel+0x867/0x8a1 init/main.c:1004 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 } ... key at: [] tasklist_lock+0x18/0x40 ... acquired at: mark_lock_irq kernel/locking/lockdep.c:3585 [inline] mark_lock+0x624/0xf10 kernel/locking/lockdep.c:3935 mark_usage kernel/locking/lockdep.c:3826 [inline] __lock_acquire+0x1ed9/0x4e00 kernel/locking/lockdep.c:4298 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x2d/0x40 kernel/locking/spinlock.c:223 send_sigurg+0x9f/0x320 fs/fcntl.c:840 sk_send_sigurg+0x76/0x300 net/core/sock.c:2855 tcp_check_urg net/ipv4/tcp_input.c:5353 [inline] tcp_urg+0x38c/0xb80 net/ipv4/tcp_input.c:5394 tcp_rcv_established+0x8f3/0x1d90 net/ipv4/tcp_input.c:5724 tcp_v4_do_rcv+0x605/0x8b0 net/ipv4/tcp_ipv4.c:1621 tcp_v4_rcv+0x2f60/0x39c0 net/ipv4/tcp_ipv4.c:2003 ip_protocol_deliver_rcu+0x57/0x880 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x220/0x360 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x1c8/0x4e0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:441 [inline] ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core+0xf5/0x160 net/core/dev.c:5187 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5301 process_backlog+0x21e/0x7a0 net/core/dev.c:6133 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x4c2/0x1070 net/core/dev.c:6639 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x192/0x1d0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:546 [inline] smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 __sanitizer_cov_trace_switch+0x32/0x70 kernel/kcov.c:309 tomoyo_domain_quota_is_ok+0x18b/0x500 security/tomoyo/util.c:1039 tomoyo_supervisor+0x2d5/0xee0 security/tomoyo/common.c:2089 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x257/0x360 security/tomoyo/file.c:573 tomoyo_path_perm+0x2f6/0x400 security/tomoyo/file.c:838 security_inode_getattr+0xeb/0x150 security/security.c:1273 vfs_getattr+0x22/0x60 fs/stat.c:117 vfs_statx+0x142/0x1e0 fs/stat.c:201 vfs_lstat include/linux/fs.h:3284 [inline] __do_sys_newlstat+0x96/0x120 fs/stat.c:364 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 stack backtrace: CPU: 1 PID: 4295 Comm: systemd-udevd Not tainted 5.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_irq_inversion_bug kernel/locking/lockdep.c:3448 [inline] check_usage_forwards.cold+0x20/0x29 kernel/locking/lockdep.c:3472 mark_lock_irq kernel/locking/lockdep.c:3585 [inline] mark_lock+0x624/0xf10 kernel/locking/lockdep.c:3935 mark_usage kernel/locking/lockdep.c:3826 [inline] __lock_acquire+0x1ed9/0x4e00 kernel/locking/lockdep.c:4298 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline] _raw_read_lock+0x2d/0x40 kernel/locking/spinlock.c:223 send_sigurg+0x9f/0x320 fs/fcntl.c:840 sk_send_sigurg+0x76/0x300 net/core/sock.c:2855 tcp_check_urg net/ipv4/tcp_input.c:5353 [inline] tcp_urg+0x38c/0xb80 net/ipv4/tcp_input.c:5394 tcp_rcv_established+0x8f3/0x1d90 net/ipv4/tcp_input.c:5724 tcp_v4_do_rcv+0x605/0x8b0 net/ipv4/tcp_ipv4.c:1621 tcp_v4_rcv+0x2f60/0x39c0 net/ipv4/tcp_ipv4.c:2003 ip_protocol_deliver_rcu+0x57/0x880 net/ipv4/ip_input.c:204 ip_local_deliver_finish+0x220/0x360 net/ipv4/ip_input.c:231 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_local_deliver+0x1c8/0x4e0 net/ipv4/ip_input.c:252 dst_input include/net/dst.h:441 [inline] ip_rcv_finish+0x1da/0x2f0 net/ipv4/ip_input.c:428 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip_rcv+0xd0/0x3c0 net/ipv4/ip_input.c:539 __netif_receive_skb_one_core+0xf5/0x160 net/core/dev.c:5187 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5301 process_backlog+0x21e/0x7a0 net/core/dev.c:6133 napi_poll net/core/dev.c:6571 [inline] net_rx_action+0x4c2/0x1070 net/core/dev.c:6639 __do_softirq+0x26c/0x9f7 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x192/0x1d0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:546 [inline] smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__sanitizer_cov_trace_switch+0x32/0x70 kernel/kcov.c:310 Code: f5 53 48 8b 46 08 48 83 f8 20 74 52 77 39 48 83 f8 08 74 43 48 83 f8 10 75 28 bf 03 00 00 00 4c 8b 65 00 31 db 4d 85 e4 74 18 <48> 8b 74 dd 10 48 83 c3 01 48 8b 4c 24 18 e8 5b fe ff ff 49 39 dc RSP: 0018:ffffc90001677820 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: 0000000000000006 RCX: ffffffff835ff8cb RDX: 0000000000000002 RSI: 0000000000000006 RDI: 0000000000000001 RBP: ffffffff886c0540 R08: ffff8880a477c540 R09: fffffbfff190139d R10: ffffffff8c809ce7 R11: fffffbfff190139c R12: 0000000000000007 R13: 000000000000013b R14: dffffc0000000000 R15: 0000000000000000 tomoyo_domain_quota_is_ok+0x18b/0x500 security/tomoyo/util.c:1039 tomoyo_supervisor+0x2d5/0xee0 security/tomoyo/common.c:2089 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline] tomoyo_path_permission security/tomoyo/file.c:587 [inline] tomoyo_path_permission+0x257/0x360 security/tomoyo/file.c:573 tomoyo_path_perm+0x2f6/0x400 security/tomoyo/file.c:838 security_inode_getattr+0xeb/0x150 security/security.c:1273 vfs_getattr+0x22/0x60 fs/stat.c:117 vfs_statx+0x142/0x1e0 fs/stat.c:201 vfs_lstat include/linux/fs.h:3284 [inline] __do_sys_newlstat+0x96/0x120 fs/stat.c:364 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x7fb970784335 Code: 69 db 2b 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 83 ff 01 48 89 f0 77 30 48 89 c7 48 89 d6 b8 06 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 03 f3 c3 90 48 8b 15 31 db 2b 00 f7 d8 64 89 RSP: 002b:00007ffcf950a2b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000006 RAX: ffffffffffffffda RBX: 000055b60776db30 RCX: 00007fb970784335 RDX: 00007ffcf950a2f0 RSI: 00007ffcf950a2f0 RDI: 000055b60776cb30 RBP: 00007ffcf950a3b0 R08: 00007fb970a43278 R09: 0000000000001010 R10: 00000000000001b0 R11: 0000000000000246 R12: 000055b60776cb30 R13: 000055b60776cb56 R14: 000055b60775f1e1 R15: 000055b60775f1e6 TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters.