====================================================== WARNING: possible circular locking dependency detected 5.12.0-rc7-syzkaller #0 Not tainted ------------------------------------------------------ syz-fuzzer/8403 is trying to acquire lock: ffff88806440b3a0 (slock-AF_INET6){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff88806440b3a0 (slock-AF_INET6){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 but task is already holding lock: ffff88802b63aca0 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] ffff88802b63aca0 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x38/0x550 net/sctp/protocol.c:626 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&net->sctp.addr_wq_lock){+.-.}-{2:2}: __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:359 [inline] sctp_destroy_sock+0x204/0x440 net/sctp/socket.c:5028 sctp_v6_destroy_sock+0x11/0x20 net/sctp/socket.c:9528 sk_common_release+0x64/0x390 net/core/sock.c:3264 sctp_close+0x4da/0x940 net/sctp/socket.c:1531 inet_release+0x12e/0x280 net/ipv4/af_inet.c:431 inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:478 __sock_release+0xcd/0x280 net/socket.c:599 sock_close+0x18/0x20 net/socket.c:1258 __fput+0x288/0x920 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:140 exit_task_work include/linux/task_work.h:30 [inline] do_exit+0xbfc/0x2a60 kernel/exit.c:825 do_group_exit+0x125/0x310 kernel/exit.c:922 get_signal+0x47f/0x2150 kernel/signal.c:2781 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:789 handle_signal_work kernel/entry/common.c:147 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (slock-AF_INET6){+.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:2937 [inline] check_prevs_add kernel/locking/lockdep.c:3060 [inline] validate_chain kernel/locking/lockdep.c:3675 [inline] __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901 lock_acquire kernel/locking/lockdep.c:5511 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476 __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:354 [inline] sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1431 expire_timers kernel/time/timer.c:1476 [inline] __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1745 __run_timers kernel/time/timer.c:1726 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1758 __do_softirq+0x29b/0x9f6 kernel/softirq.c:345 invoke_softirq kernel/softirq.c:221 [inline] __irq_exit_rcu kernel/softirq.c:422 [inline] irq_exit_rcu+0x134/0x200 kernel/softirq.c:434 sysvec_apic_timer_interrupt+0x45/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&net->sctp.addr_wq_lock); lock(slock-AF_INET6); lock(&net->sctp.addr_wq_lock); lock(slock-AF_INET6); *** DEADLOCK *** 2 locks held by syz-fuzzer/8403: #0: ffffc9000164fcc0 ((&net->sctp.addr_wq_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:35 [inline] #0: ffffc9000164fcc0 ((&net->sctp.addr_wq_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x6b0 kernel/time/timer.c:1421 #1: ffff88802b63aca0 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] #1: ffff88802b63aca0 (&net->sctp.addr_wq_lock){+.-.}-{2:2}, at: sctp_addr_wq_timeout_handler+0x38/0x550 net/sctp/protocol.c:626 stack backtrace: CPU: 1 PID: 8403 Comm: syz-fuzzer Not tainted 5.12.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2128 check_prev_add kernel/locking/lockdep.c:2937 [inline] check_prevs_add kernel/locking/lockdep.c:3060 [inline] validate_chain kernel/locking/lockdep.c:3675 [inline] __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901 lock_acquire kernel/locking/lockdep.c:5511 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476 __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:354 [inline] sctp_addr_wq_timeout_handler+0x1a1/0x550 net/sctp/protocol.c:666 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1431 expire_timers kernel/time/timer.c:1476 [inline] __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1745 __run_timers kernel/time/timer.c:1726 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1758 __do_softirq+0x29b/0x9f6 kernel/softirq.c:345 invoke_softirq kernel/softirq.c:221 [inline] __irq_exit_rcu kernel/softirq.c:422 [inline] irq_exit_rcu+0x134/0x200 kernel/softirq.c:434 sysvec_apic_timer_interrupt+0x45/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 RIP: 0033:0x412ac0 Code: 79 10 00 0f 84 46 02 00 00 48 8b 54 24 40 e9 a1 00 00 00 4d 8d 54 24 01 48 89 d9 4c 89 cf 4c 89 db 4d 89 d1 66 0f 1f 44 00 00 <49> 83 f9 08 0f 83 bd 01 00 00 84 03 46 0f b6 14 0b 41 80 fa 01 0f RSP: 002b:000000c00d070f58 EFLAGS: 00000246 RAX: e1f4945731bd94cb RBX: 000000c00ad47080 RCX: 0000000000000000 RDX: 000000000071d7a0 RSI: 000000c00ad66ab0 RDI: 0000000000000000 RBP: 000000c00d070f88 R08: 0000000000000058 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000075 R12: 00000000000000f5 R13: 0000000000000000 R14: 000000000094728c R15: 0000000000000000