================================ WARNING: inconsistent lock state 5.9.0-rc5-next-20200916-syzkaller #0 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-R} -> {SOFTIRQ-ON-W} usage. syz-executor.1/14523 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff88805d95b750 (&s->seqcount#11){+.+-}-{0:0}, at: xfrm_user_rcv_msg+0x414/0x700 net/xfrm/xfrm_user.c:2684 {IN-SOFTIRQ-R} state was registered at: lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398 seqcount_lockdep_reader_access+0x139/0x1a0 include/linux/seqlock.h:103 xfrm_policy_lookup_inexact_addr+0x57/0x200 net/xfrm/xfrm_policy.c:1909 xfrm_policy_find_inexact_candidates+0xac/0x1d0 net/xfrm/xfrm_policy.c:1953 xfrm_policy_lookup_bytype+0x4b8/0xa40 net/xfrm/xfrm_policy.c:2108 xfrm_policy_lookup net/xfrm/xfrm_policy.c:2144 [inline] xfrm_bundle_lookup net/xfrm/xfrm_policy.c:2944 [inline] xfrm_lookup_with_ifid+0xaa1/0x2100 net/xfrm/xfrm_policy.c:3085 icmp6_dst_alloc+0x489/0x6c0 net/ipv6/route.c:3187 ndisc_send_skb+0x1207/0x1720 net/ipv6/ndisc.c:486 ndisc_send_rs+0x12e/0x700 net/ipv6/ndisc.c:700 addrconf_rs_timer+0x2ec/0x7c0 net/ipv6/addrconf.c:3873 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1413 expire_timers kernel/time/timer.c:1458 [inline] __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1755 __run_timers kernel/time/timer.c:1736 [inline] run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1768 __do_softirq+0x202/0xa42 kernel/softirq.c:298 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:393 [inline] __irq_exit_rcu kernel/softirq.c:423 [inline] irq_exit_rcu+0x235/0x280 kernel/softirq.c:435 sysvec_apic_timer_interrupt+0x51/0xf0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 lock_is_held_type+0x21/0xf0 kernel/locking/lockdep.c:5426 lock_is_held include/linux/lockdep.h:271 [inline] rcu_read_lock_sched_held+0x3a/0xb0 kernel/rcu/update.c:123 trace_lock_release include/trace/events/lock.h:58 [inline] lock_release+0x65f/0x890 kernel/locking/lockdep.c:5409 __might_fault mm/memory.c:4871 [inline] __might_fault+0x144/0x180 mm/memory.c:4856 __clear_user+0x1e/0x70 arch/x86/lib/usercopy_64.c:21 clear_user arch/x86/lib/usercopy_64.c:57 [inline] clear_user+0xa8/0x130 arch/x86/lib/usercopy_64.c:52 read_zero+0x71/0x140 drivers/char/mem.c:738 vfs_read+0x1b5/0x570 fs/read_write.c:493 ksys_read+0x12d/0x250 fs/read_write.c:624 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 irq event stamp: 103 hardirqs last enabled at (103): [] __local_bh_enable_ip+0x10f/0x1f0 kernel/softirq.c:200 hardirqs last disabled at (101): [] __local_bh_enable_ip+0x154/0x1f0 kernel/softirq.c:177 softirqs last enabled at (102): [] rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline] softirqs last enabled at (102): [] __dev_queue_xmit+0x1a7e/0x2d10 net/core/dev.c:4164 softirqs last disabled at (98): [] __dev_queue_xmit+0x1d7/0x2d10 net/core/dev.c:4072 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&s->seqcount#11); lock(&s->seqcount#11); *** DEADLOCK *** 2 locks held by syz-executor.1/14523: #0: ffff88805d95bae8 (&net->xfrm.xfrm_cfg_mutex){+.+.}-{3:3}, at: xfrm_netlink_rcv+0x5c/0x90 net/xfrm/xfrm_user.c:2691 #1: ffff88805d95b798 (&(&net->xfrm.policy_hthresh.lock)->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #1: ffff88805d95b798 (&(&net->xfrm.policy_hthresh.lock)->lock){+.+.}-{2:2}, at: write_seqlock include/linux/seqlock.h:882 [inline] #1: ffff88805d95b798 (&(&net->xfrm.policy_hthresh.lock)->lock){+.+.}-{2:2}, at: xfrm_set_spdinfo+0x2b8/0x660 net/xfrm/xfrm_user.c:1185 stack backtrace: CPU: 0 PID: 14523 Comm: syz-executor.1 Not tainted 5.9.0-rc5-next-20200916-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+0x198/0x1fb lib/dump_stack.c:118 print_usage_bug kernel/locking/lockdep.c:4377 [inline] valid_state kernel/locking/lockdep.c:3705 [inline] mark_lock_irq kernel/locking/lockdep.c:3914 [inline] mark_lock.cold+0x6f/0x10d kernel/locking/lockdep.c:4375 mark_usage kernel/locking/lockdep.c:4278 [inline] __lock_acquire+0x882/0x55d0 kernel/locking/lockdep.c:4750 lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398 write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline] write_seqcount_t_begin include/linux/seqlock.h:535 [inline] write_seqlock include/linux/seqlock.h:883 [inline] xfrm_set_spdinfo+0x302/0x660 net/xfrm/xfrm_user.c:1185 xfrm_user_rcv_msg+0x414/0x700 net/xfrm/xfrm_user.c:2684 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470 xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2692 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:671 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2362 ___sys_sendmsg+0xf3/0x170 net/socket.c:2416 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2449 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5f9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fd204cf9c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000002cf80 RCX: 000000000045d5f9 RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffc1b9ca9df R14: 00007fd204cfa9c0 R15: 000000000118cf4c