====================================================== WARNING: possible circular locking dependency detected 4.14.198-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/10446 is trying to acquire lock: (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}, at: [] spin_lock include/linux/spinlock.h:317 [inline] (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}, at: [] __dev_xmit_skb net/core/dev.c:3198 [inline] (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}, at: [] __dev_queue_xmit+0x1ef5/0x2480 net/core/dev.c:3489 but task is already holding lock: (_xmit_ETHER#2){+.-.}, at: [] spin_lock include/linux/spinlock.h:317 [inline] (_xmit_ETHER#2){+.-.}, at: [] __netif_tx_lock include/linux/netdevice.h:3536 [inline] (_xmit_ETHER#2){+.-.}, at: [] sch_direct_xmit+0x1db/0x500 net/sched/sch_generic.c:184 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (_xmit_ETHER#2){+.-.}: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:152 spin_lock include/linux/spinlock.h:317 [inline] __netif_tx_lock include/linux/netdevice.h:3536 [inline] sch_direct_xmit+0x1db/0x500 net/sched/sch_generic.c:184 __dev_xmit_skb net/core/dev.c:3214 [inline] __dev_queue_xmit+0x1ab0/0x2480 net/core/dev.c:3489 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 ip_finish_output+0x37b/0xc30 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x220/0xcb0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:470 [inline] ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124 ip_send_skb+0x3a/0xc0 net/ipv4/ip_output.c:1422 udp_send_skb+0x601/0xb70 net/ipv4/udp.c:833 udp_sendmsg+0x15a3/0x1c00 net/ipv4/udp.c:1057 inet_sendmsg+0x11a/0x4e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 ___sys_sendmsg+0x326/0x800 net/socket.c:2062 __sys_sendmmsg+0x129/0x330 net/socket.c:2152 SYSC_sendmmsg net/socket.c:2183 [inline] SyS_sendmmsg+0x2f/0x50 net/socket.c:2178 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:152 spin_lock include/linux/spinlock.h:317 [inline] __dev_xmit_skb net/core/dev.c:3198 [inline] __dev_queue_xmit+0x1ef5/0x2480 net/core/dev.c:3489 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 ip_finish_output+0x37b/0xc30 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x220/0xcb0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:470 [inline] ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124 iptunnel_xmit+0x5cc/0x950 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0xef8/0x3440 net/ipv4/ip_tunnel.c:799 erspan_xmit net/ipv4/ip_gre.c:750 [inline] erspan_xmit+0x43e/0x1090 net/ipv4/ip_gre.c:725 __netdev_start_xmit include/linux/netdevice.h:4039 [inline] netdev_start_xmit include/linux/netdevice.h:4048 [inline] xmit_one net/core/dev.c:3005 [inline] dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021 sch_direct_xmit+0x251/0x500 net/sched/sch_generic.c:186 __dev_xmit_skb net/core/dev.c:3214 [inline] __dev_queue_xmit+0x1ab0/0x2480 net/core/dev.c:3489 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 ip_finish_output+0x37b/0xc30 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x220/0xcb0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:470 [inline] ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124 ip_send_skb+0x3a/0xc0 net/ipv4/ip_output.c:1422 udp_send_skb+0x601/0xb70 net/ipv4/udp.c:833 udp_sendmsg+0x15a3/0x1c00 net/ipv4/udp.c:1057 inet_sendmsg+0x11a/0x4e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 ___sys_sendmsg+0x326/0x800 net/socket.c:2062 __sys_sendmmsg+0x129/0x330 net/socket.c:2152 SYSC_sendmmsg net/socket.c:2183 [inline] SyS_sendmmsg+0x2f/0x50 net/socket.c:2178 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(_xmit_ETHER#2); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(_xmit_ETHER#2); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** 6 locks held by syz-executor.3/10446: #0: (rcu_read_lock_bh){....}, at: [] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #0: (rcu_read_lock_bh){....}, at: [] ip_finish_output2+0x23f/0x12f0 net/ipv4/ip_output.c:213 #1: (rcu_read_lock_bh){....}, at: [] __dev_queue_xmit+0x1ac/0x2480 net/core/dev.c:3455 #2: (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: [] neigh_hh_output include/net/neighbour.h:490 [inline] #2: (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: [] neigh_output include/net/neighbour.h:498 [inline] #2: (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: [] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 #3: (_xmit_ETHER#2){+.-.}, at: [] spin_lock include/linux/spinlock.h:317 [inline] #3: (_xmit_ETHER#2){+.-.}, at: [] __netif_tx_lock include/linux/netdevice.h:3536 [inline] #3: (_xmit_ETHER#2){+.-.}, at: [] sch_direct_xmit+0x1db/0x500 net/sched/sch_generic.c:184 #4: (rcu_read_lock_bh){....}, at: [] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #4: (rcu_read_lock_bh){....}, at: [] ip_finish_output2+0x23f/0x12f0 net/ipv4/ip_output.c:213 #5: (rcu_read_lock_bh){....}, at: [] __dev_queue_xmit+0x1ac/0x2480 net/core/dev.c:3455 stack backtrace: CPU: 0 PID: 10446 Comm: syz-executor.3 Not tainted 4.14.198-syzkaller #0 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+0x1b2/0x283 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:152 spin_lock include/linux/spinlock.h:317 [inline] __dev_xmit_skb net/core/dev.c:3198 [inline] __dev_queue_xmit+0x1ef5/0x2480 net/core/dev.c:3489 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 ip_finish_output+0x37b/0xc30 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x220/0xcb0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:470 [inline] ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124 iptunnel_xmit+0x5cc/0x950 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0xef8/0x3440 net/ipv4/ip_tunnel.c:799 erspan_xmit net/ipv4/ip_gre.c:750 [inline] erspan_xmit+0x43e/0x1090 net/ipv4/ip_gre.c:725 __netdev_start_xmit include/linux/netdevice.h:4039 [inline] netdev_start_xmit include/linux/netdevice.h:4048 [inline] xmit_one net/core/dev.c:3005 [inline] dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021 sch_direct_xmit+0x251/0x500 net/sched/sch_generic.c:186 __dev_xmit_skb net/core/dev.c:3214 [inline] __dev_queue_xmit+0x1ab0/0x2480 net/core/dev.c:3489 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip_finish_output2+0x9db/0x12f0 net/ipv4/ip_output.c:229 ip_finish_output+0x37b/0xc30 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip_mc_output+0x220/0xcb0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:470 [inline] ip_local_out+0x93/0x170 net/ipv4/ip_output.c:124 ip_send_skb+0x3a/0xc0 net/ipv4/ip_output.c:1422 udp_send_skb+0x601/0xb70 net/ipv4/udp.c:833 udp_sendmsg+0x15a3/0x1c00 net/ipv4/udp.c:1057 inet_sendmsg+0x11a/0x4e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 ___sys_sendmsg+0x326/0x800 net/socket.c:2062 __sys_sendmmsg+0x129/0x330 net/socket.c:2152 SYSC_sendmmsg net/socket.c:2183 [inline] SyS_sendmmsg+0x2f/0x50 net/socket.c:2178 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45d5f9 RSP: 002b:00007ff386ce3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000027a40 RCX: 000000000045d5f9 RDX: 000000000800001d RSI: 0000000020007fc0 RDI: 0000000000000003 RBP: 000000000118d028 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec R13: 00007ffd89fd96af R14: 00007ff386ce49c0 R15: 000000000118cfec ptrace attach of "/root/syz-executor.4"[10504] was attempted by "/root/syz-executor.4"[10506] netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'. kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x65 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x64 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x65 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x64 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x65 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x64 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x65 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x64 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x65 kvm [10701]: vcpu0, guest rIP: 0x14c disabled perfctr wrmsr: 0xc2 data 0x64