input: syz1 as /devices/virtual/input/input70
===============================
[ INFO: suspicious RCU usage. ]
4.9.141+ #1 Not tainted
-------------------------------
net/ipv6/ip6_fib.c:1471 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
4 locks held by syz-executor.3/2123:
 #0:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff812629ba>] lockdep_copy_map include/linux/lockdep.h:165 [inline]
 #0:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff812629ba>] call_timer_fn+0xda/0x6e0 kernel/time/timer.c:1309
 #1:  (&(&net->ipv6.fib6_gc_lock)->rlock[  561.804689] syz-executor.2 (20110) used greatest stack depth: 22440 bytes left
){+.-...}, at: [<ffffffff826ef615>] spin_lock_bh include/linux/spinlock.h:307 [inline]
){+.-...}, at: [<ffffffff826ef615>] fib6_run_gc+0xa5/0x2c0 net/ipv6/ip6_fib.c:1816
 #2:  (rcu_read_lock){......}, at: [<ffffffff826e6c70>] __fib6_clean_all+0x0/0x220 net/ipv6/ip6_fib.c:1703
 #3:  (&tb->tb6_lock){++--..}, at: [<ffffffff826e6d50>] __fib6_clean_all+0xe0/0x220 net/ipv6/ip6_fib.c:1717

stack backtrace:
CPU: 1 PID: 2123 Comm: syz-executor.3 Not tainted 4.9.141+ #1
 ffff8801db7078c8 ffffffff81b42e79 ffff8801d7868000 0000000000000000
 0000000000000002 ffffffff82cc2480 ffffed003b6e0f67 ffff8801db7078f8
 ffffffff813fe948 ffff8801d6e3d880 ffff8801db707ae8 ffff8801d6e3d880
Call Trace:
 <IRQ> [  561.879281]  [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  561.879281]  [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff813fe948>] lockdep_rcu_suspicious.cold.32+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff826eed80>] fib6_del+0x810/0xb10 net/ipv6/ip6_fib.c:1470
 [<ffffffff826ef2a0>] fib6_clean_node+0x220/0x4c0 net/ipv6/ip6_fib.c:1657
 [<ffffffff826e6545>] fib6_walk_continue+0x3e5/0x640 net/ipv6/ip6_fib.c:1583
 [<ffffffff826e6b01>] fib6_walk+0x91/0xf0 net/ipv6/ip6_fib.c:1628
 [<ffffffff826e6c33>] fib6_clean_tree+0xd3/0x110 net/ipv6/ip6_fib.c:1702
 [<ffffffff826e6d69>] __fib6_clean_all+0xf9/0x220 net/ipv6/ip6_fib.c:1718
 [<ffffffff826ef687>] fib6_clean_all net/ipv6/ip6_fib.c:1729 [inline]
 [<ffffffff826ef687>] fib6_run_gc+0x117/0x2c0 net/ipv6/ip6_fib.c:1826
 [<ffffffff826ef84c>] fib6_gc_timer_cb+0x1c/0x20 net/ipv6/ip6_fib.c:1841
 [<ffffffff81262a43>] call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319
 [<ffffffff812631f4>] expire_timers+0x234/0x580 kernel/time/timer.c:1359
 [<ffffffff81263748>] __run_timers kernel/time/timer.c:1674 [inline]
 [<ffffffff81263748>] run_timer_softirq+0x208/0x5e0 kernel/time/timer.c:1687
 [<ffffffff8281cb9e>] __do_softirq+0x20e/0x964 kernel/softirq.c:288
 [<ffffffff810efdbc>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff810efdbc>] irq_exit+0x11c/0x150 kernel/softirq.c:409
 [<ffffffff8281b771>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff8281b771>] smp_apic_timer_interrupt+0x81/0xb0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff8281902d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  562.155640]  [<ffffffff811edfa0>] ? remove_wait_queue+0x10/0x1b0 kernel/sched/wait.c:46
 [<ffffffff810ec86f>] do_wait+0x2ff/0x950 kernel/exit.c:1585
 [<ffffffff810eda0b>] SYSC_wait4 kernel/exit.c:1693 [inline]
 [<ffffffff810eda0b>] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1658
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
input: syz1 as /devices/virtual/input/input71
binder: 20449:20462 ioctl 41009432 200004c0 returned -22
binder: undelivered TRANSACTION_COMPLETE
binder: 20449:20460 ioctl 41009432 200004c0 returned -22
binder: undelivered TRANSACTION_COMPLETE
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.0'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.0'.