============================================= [ INFO: possible recursive locking detected ] 4.9.182+ #2 Not tainted --------------------------------------------- syz-executor.2/19284 is trying to acquire lock: (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] spin_lock include/linux/spinlock.h:302 [inline] (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __dev_queue_xmit+0x1116/0x1bd0 net/core/dev.c:3469 but task is already holding lock: (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] spin_lock include/linux/spinlock.h:302 [inline] (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __dev_queue_xmit+0x1116/0x1bd0 net/core/dev.c:3469 audit: type=1400 audit(2000001759.158:9428): avc: denied { create } for pid=19266 comm="syz-executor.3" 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 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_TUNNEL6#2); lock(_xmit_TUNNEL6#2); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.2/19284: #0: (rcu_read_lock_bh){......}, at: [<00000000d7e08741>] ip_finish_output2+0x20b/0x1280 net/ipv4/ip_output.c:198 #1: (rcu_read_lock_bh){......}, at: [<00000000fee16af2>] __dev_queue_xmit+0x1d4/0x1bd0 net/core/dev.c:3407 #2: (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] spin_lock include/linux/spinlock.h:302 [inline] #2: (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] #2: (_xmit_TUNNEL6#2){+.-...}, at: [<000000006126ab70>] __dev_queue_xmit+0x1116/0x1bd0 net/core/dev.c:3469 #3: (slock-AF_INET){+.-...}, at: [<00000000fbb65300>] spin_trylock include/linux/spinlock.h:312 [inline] #3: (slock-AF_INET){+.-...}, at: [<00000000fbb65300>] icmp_xmit_lock net/ipv4/icmp.c:220 [inline] #3: (slock-AF_INET){+.-...}, at: [<00000000fbb65300>] __icmp_send+0x48b/0x1420 net/ipv4/icmp.c:656 #4: (rcu_read_lock_bh){......}, at: [<00000000d7e08741>] ip_finish_output2+0x20b/0x1280 net/ipv4/ip_output.c:198 #5: (rcu_read_lock_bh){......}, at: [<00000000fee16af2>] __dev_queue_xmit+0x1d4/0x1bd0 net/core/dev.c:3407 stack backtrace: CPU: 0 PID: 19284 Comm: syz-executor.2 Not tainted 4.9.182+ #2 ffff88016d726560 ffffffff81b57e21 ffffffff8424eec0 ffffffff83cceaf0 ffffffff83cceaf0 58aa530756ef9256 ffff88016256df00 ffff88016d726700 ffffffff814072d0 0000000000000005 ffff88016256df00 ffff88016d726720 Call Trace: [<00000000acad6ac6>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000acad6ac6>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000ecc02d7f>] print_deadlock_bug kernel/locking/lockdep.c:1727 [inline] [<00000000ecc02d7f>] check_deadlock kernel/locking/lockdep.c:1771 [inline] [<00000000ecc02d7f>] validate_chain kernel/locking/lockdep.c:2249 [inline] [<00000000ecc02d7f>] __lock_acquire.cold+0x384/0x734 kernel/locking/lockdep.c:3345 [<00000000cd4d76d7>] lock_acquire+0x133/0x3d0 kernel/locking/lockdep.c:3756 [<00000000b089456c>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline] [<00000000b089456c>] _raw_spin_lock+0x38/0x50 kernel/locking/spinlock.c:151 [<000000006126ab70>] spin_lock include/linux/spinlock.h:302 [inline] [<000000006126ab70>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] [<000000006126ab70>] __dev_queue_xmit+0x1116/0x1bd0 net/core/dev.c:3469 [<0000000043b95c85>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3506 [<00000000dd0316f4>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1366 [<0000000075de95db>] dst_neigh_output include/net/dst.h:470 [inline] [<0000000075de95db>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:225 [<00000000f795c047>] ip_finish_output+0x3c4/0xce0 net/ipv4/ip_output.c:313 [<000000009f27fe75>] NF_HOOK_COND include/linux/netfilter.h:246 [inline] [<000000009f27fe75>] ip_output+0x1ec/0x5b0 net/ipv4/ip_output.c:401 [<00000000fbc48854>] dst_output include/net/dst.h:507 [inline] [<00000000fbc48854>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:124 [<000000003778c0ba>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1490 [<00000000e5b176b7>] ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1510 [<00000000fce7fe73>] icmp_push_reply+0x39e/0x510 net/ipv4/icmp.c:381 [<000000001f16d6a2>] __icmp_send+0xad9/0x1420 net/ipv4/icmp.c:728 [<00000000a1505e6d>] ipv4_send_dest_unreach net/ipv4/route.c:1202 [inline] [<00000000a1505e6d>] ipv4_link_failure+0x460/0x850 net/ipv4/route.c:1209 [<000000005e162650>] dst_link_failure include/net/dst.h:490 [inline] [<000000005e162650>] vti6_xmit net/ipv6/ip6_vti.c:522 [inline] [<000000005e162650>] vti6_tnl_xmit+0xb08/0x17f0 net/ipv6/ip6_vti.c:561 [<000000004d70736b>] __netdev_start_xmit include/linux/netdevice.h:4072 [inline] [<000000004d70736b>] netdev_start_xmit include/linux/netdevice.h:4081 [inline] [<000000004d70736b>] xmit_one net/core/dev.c:2977 [inline] [<000000004d70736b>] dev_hard_start_xmit+0x195/0x8b0 net/core/dev.c:2993 [<00000000f111ad54>] __dev_queue_xmit+0x11a3/0x1bd0 net/core/dev.c:3473 [<0000000043b95c85>] dev_queue_xmit+0x18/0x20 net/core/dev.c:3506 [<00000000dd0316f4>] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1366 [<0000000075de95db>] dst_neigh_output include/net/dst.h:470 [inline] [<0000000075de95db>] ip_finish_output2+0x6a2/0x1280 net/ipv4/ip_output.c:225 [<00000000f795c047>] ip_finish_output+0x3c4/0xce0 net/ipv4/ip_output.c:313 [<000000009f27fe75>] NF_HOOK_COND include/linux/netfilter.h:246 [inline] [<000000009f27fe75>] ip_output+0x1ec/0x5b0 net/ipv4/ip_output.c:401 [<00000000fbc48854>] dst_output include/net/dst.h:507 [inline] [<00000000fbc48854>] ip_local_out+0x9c/0x180 net/ipv4/ip_output.c:124 [<000000003778c0ba>] ip_send_skb+0x3e/0xc0 net/ipv4/ip_output.c:1490 [<000000005587ba5c>] udp_send_skb+0x4fc/0xc60 net/ipv4/udp.c:833 [<000000000f08d41c>] udp_sendmsg+0x1634/0x1c60 net/ipv4/udp.c:1057 [<000000002a730f63>] udpv6_sendmsg+0x12af/0x2430 net/ipv6/udp.c:1086 [<00000000adcf8811>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:766 [<000000006d2a7858>] sock_sendmsg_nosec net/socket.c:649 [inline] [<000000006d2a7858>] sock_sendmsg+0xbe/0x110 net/socket.c:659 [<000000009883150c>] ___sys_sendmsg+0x387/0x8b0 net/socket.c:1983 [<00000000f1cf7596>] __sys_sendmmsg+0x164/0x3d0 net/socket.c:2073 [<00000000cc872fc8>] SYSC_sendmmsg net/socket.c:2104 [inline] [<00000000cc872fc8>] SyS_sendmmsg+0x35/0x60 net/socket.c:2099 [<00000000a43a18e1>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000ce6ec14f>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb