=============================== [ INFO: suspicious RCU usage. ] 4.4.174+ #4 Not tainted ------------------------------- net/ipv6/ip6_fib.c:1465 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 6 locks held by syz-executor.2/2137: #0: (tasklist_lock){.+.?..}, at: [] do_wait+0x2be/0xa00 kernel/exit.c:1515 #1: (rcu_read_lock){......}, at: [] task_has_perm+0x0/0x330 security/selinux/hooks.c:5620 #2: (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [] lockdep_copy_map include/linux/lockdep.h:165 [inline] #2: (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [] call_timer_fn+0xde/0x850 kernel/time/timer.c:1175 #3: (fib6_gc_lock){+.-...}, at: [] spin_lock_bh include/linux/spinlock.h:307 [inline] #3: (fib6_gc_lock){+.-...}, at: [] fib6_run_gc+0x3a/0x230 net/ipv6/ip6_fib.c:1811 #4: (rcu_read_lock){......}, at: [] __fib6_clean_all+0x0/0x240 net/ipv6/ip6_fib.c:1698 #5: (&tb->tb6_lock){++--..}, at: [] __fib6_clean_all+0xe8/0x240 net/ipv6/ip6_fib.c:1712 stack backtrace: CPU: 1 PID: 2137 Comm: syz-executor.2 Not tainted 4.4.174+ #4 0000000000000000 58a4db7bd9716dbf ffff8801db707940 ffffffff81aad1a1 ffff8801d42688c0 0000000000000000 0000000000000001 00000000000005b9 ffff8800babadf00 ffff8801db707970 ffffffff813ab7d6 ffff8801db707b90 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4305 [] fib6_del+0x7ea/0xae0 net/ipv6/ip6_fib.c:1465 [] fib6_clean_node+0x29c/0x500 net/ipv6/ip6_fib.c:1652 [] fib6_walk_continue+0x3e0/0x630 net/ipv6/ip6_fib.c:1578 [] fib6_walk+0x91/0xe0 net/ipv6/ip6_fib.c:1623 [] fib6_clean_tree+0xe8/0x120 net/ipv6/ip6_fib.c:1697 [] __fib6_clean_all+0x100/0x240 net/ipv6/ip6_fib.c:1713 [] fib6_clean_all net/ipv6/ip6_fib.c:1724 [inline] [] fib6_run_gc+0xaf/0x230 net/ipv6/ip6_fib.c:1821 [] fib6_gc_timer_cb+0x1d/0x30 net/ipv6/ip6_fib.c:1836 [] call_timer_fn+0x18d/0x850 kernel/time/timer.c:1185 [] __run_timers kernel/time/timer.c:1261 [inline] [] run_timer_softirq+0x51f/0xb70 kernel/time/timer.c:1444 [] __do_softirq+0x226/0xa3f kernel/softirq.c:273 [] invoke_softirq kernel/softirq.c:350 [inline] [] irq_exit+0x10a/0x150 kernel/softirq.c:391 [] exiting_irq arch/x86/include/asm/apic.h:652 [inline] [] smp_apic_timer_interrupt+0x7e/0xb0 arch/x86/kernel/apic/apic.c:926 [] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:768 [] ? check_preemption_disabled+0x3c/0x200 lib/smp_processor_id.c:51 [] rcu_read_lock include/linux/rcupdate.h:862 [inline] [] task_has_perm+0x24b/0x330 security/selinux/hooks.c:1521 [] selinux_task_wait+0x24/0x30 security/selinux/hooks.c:3763 [] security_task_wait+0x73/0xb0 security/security.c:993 [] wait_consider_task+0x28b/0x35b0 kernel/exit.c:1334 [] do_wait_thread kernel/exit.c:1447 [inline] [] do_wait+0x350/0xa00 kernel/exit.c:1518 [] SYSC_wait4 kernel/exit.c:1649 [inline] [] SyS_wait4+0x144/0x210 kernel/exit.c:1614 [] entry_SYSCALL_64_fastpath+0x1e/0x9a audit_printk_skb: 24 callbacks suppressed audit: type=1400 audit(1552850412.034:2227): avc: denied { create } for pid=27170 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0 audit: type=1400 audit(1552850412.644:2228): avc: denied { create } for pid=27205 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0 audit: type=1400 audit(1552850415.254:2229): avc: denied { create } for pid=27216 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0 audit: type=1400 audit(1552850415.834:2230): avc: denied { create } for pid=27246 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0 audit: type=1400 audit(1552850416.434:2231): avc: denied { create } for pid=27274 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0