audit: type=1400 audit(1514682099.438:9): avc:  denied  { write } for  pid=3183 comm="syzkaller177048" path="socket:[10926]" dev="sockfs" ino=10926 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=1
=============================
WARNING: suspicious RCU usage
4.15.0-rc5+ #170 Not tainted
-----------------------------
net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syzkaller177048/3183:
 #0:  (cb_lock){++++}, at: [<00000000207920d7>] genl_rcv+0x19/0x40 net/netlink/genetlink.c:634
 #1:  (genl_mutex){+.+.}, at: [<00000000e1c96fbd>] genl_lock net/netlink/genetlink.c:33 [inline]
 #1:  (genl_mutex){+.+.}, at: [<00000000e1c96fbd>] genl_rcv_msg+0x115/0x140 net/netlink/genetlink.c:622

stack backtrace:
CPU: 1 PID: 3183 Comm: syzkaller177048 Not tainted 4.15.0-rc5+ #170
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
 tipc_bearer_find+0x2b4/0x3b0 net/tipc/bearer.c:177
 tipc_nl_compat_link_set+0x329/0x9f0 net/tipc/netlink_compat.c:729
 __tipc_nl_compat_doit net/tipc/netlink_compat.c:288 [inline]
 tipc_nl_compat_doit+0x15b/0x660 net/tipc/netlink_compat.c:335
 tipc_nl_compat_handle net/tipc/netlink_compat.c:1119 [inline]
 tipc_nl_compat_recv+0x112f/0x18f0 net/tipc/netlink_compat.c:1201
 genl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599
 genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624
 netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2441
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:635
 netlink_unicast_kernel net/netlink/af_netlink.c:1308 [inline]
 netlink_unicast+0x4be/0x6a0 net/netlink/af_netlink.c:1334
 netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1897
 sock_sendmsg_nosec net/socket.c:628 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:638
 sock_write_iter+0x31a/0x5d0 net/socket.c:907
 call_write_iter include/linux/fs.h:1772 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:482
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x444aa9
RSP: 002b:00007ffec9699848 EFLAGS: 00000207 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000444aa9
RDX: 0000000000000029 RSI: 000000002060be48 RDI: 00000