============================================ WARNING: possible recursive locking detected 4.19.211-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/16067 is trying to acquire lock: 000000007db2ebf6 (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] 000000007db2ebf6 (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3842 [inline] 000000007db2ebf6 (_xmit_ETHER#2){+.-.}, at: sch_direct_xmit+0x254/0xf70 net/sched/sch_generic.c:330 but task is already holding lock: 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3842 [inline] 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: sch_direct_xmit+0x254/0xf70 net/sched/sch_generic.c:330 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 9 locks held by syz-executor.0/16067: #0: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #0: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: ip_finish_output2+0x28d/0x15a0 net/ipv4/ip_output.c:214 #1: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x1e2/0x2e00 net/core/dev.c:3773 #2: 00000000f450caae (&(&sch->seqlock)->rlock){+...}, at: spin_trylock include/linux/spinlock.h:339 [inline] #2: 00000000f450caae (&(&sch->seqlock)->rlock){+...}, at: qdisc_run_begin include/net/sch_generic.h:130 [inline] #2: 00000000f450caae (&(&sch->seqlock)->rlock){+...}, at: qdisc_run include/net/pkt_sched.h:119 [inline] #2: 00000000f450caae (&(&sch->seqlock)->rlock){+...}, at: __dev_xmit_skb net/core/dev.c:3451 [inline] #2: 00000000f450caae (&(&sch->seqlock)->rlock){+...}, at: __dev_queue_xmit+0x278b/0x2e00 net/core/dev.c:3807 #3: 00000000b6c3076a (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: neigh_resolve_output+0x55a/0x910 net/core/neighbour.c:1374 #4: 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #4: 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3842 [inline] #4: 00000000cbfd359b (_xmit_ETHER#2){+.-.}, at: sch_direct_xmit+0x254/0xf70 net/sched/sch_generic.c:330 #5: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #5: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: ip_finish_output2+0x28d/0x15a0 net/ipv4/ip_output.c:214 #6: 00000000e31a44f7 (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x1e2/0x2e00 net/core/dev.c:3773 #7: 00000000cb6fb0f7 (&(&sch->seqlock)->rlock){+...}, at: spin_trylock include/linux/spinlock.h:339 [inline] #7: 00000000cb6fb0f7 (&(&sch->seqlock)->rlock){+...}, at: qdisc_run_begin include/net/sch_generic.h:130 [inline] #7: 00000000cb6fb0f7 (&(&sch->seqlock)->rlock){+...}, at: qdisc_run include/net/pkt_sched.h:119 [inline] #7: 00000000cb6fb0f7 (&(&sch->seqlock)->rlock){+...}, at: __dev_xmit_skb net/core/dev.c:3451 [inline] #7: 00000000cb6fb0f7 (&(&sch->seqlock)->rlock){+...}, at: __dev_queue_xmit+0x278b/0x2e00 net/core/dev.c:3807 #8: 000000000c893b42 (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: neigh_resolve_output+0x55a/0x910 net/core/neighbour.c:1374 stack backtrace: CPU: 1 PID: 16067 Comm: syz-executor.0 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:1764 [inline] check_deadlock kernel/locking/lockdep.c:1808 [inline] validate_chain kernel/locking/lockdep.c:2404 [inline] __lock_acquire.cold+0x121/0x57e kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __netif_tx_lock include/linux/netdevice.h:3842 [inline] sch_direct_xmit+0x254/0xf70 net/sched/sch_generic.c:330 qdisc_restart net/sched/sch_generic.c:395 [inline] __qdisc_run+0x4d0/0x1640 net/sched/sch_generic.c:403 qdisc_run include/net/pkt_sched.h:120 [inline] __dev_xmit_skb net/core/dev.c:3451 [inline] __dev_queue_xmit+0x2102/0x2e00 net/core/dev.c:3807 neigh_resolve_output+0x55a/0x910 net/core/neighbour.c:1374 neigh_output include/net/neighbour.h:501 [inline] ip_finish_output2+0xd76/0x15a0 net/ipv4/ip_output.c:230 ip_finish_output+0xae9/0x10b0 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_output+0x203/0x5f0 net/ipv4/ip_output.c:406 dst_output include/net/dst.h:455 [inline] ip_local_out+0xaf/0x170 net/ipv4/ip_output.c:125 iptunnel_xmit+0x63b/0x9d0 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0x13ad/0x3850 net/ipv4/ip_tunnel.c:790 erspan_xmit+0xd6e/0x27e0 net/ipv4/ip_gre.c:759 __netdev_start_xmit include/linux/netdevice.h:4349 [inline] netdev_start_xmit include/linux/netdevice.h:4363 [inline] xmit_one net/core/dev.c:3256 [inline] dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272 sch_direct_xmit+0x2d6/0xf70 net/sched/sch_generic.c:332 qdisc_restart net/sched/sch_generic.c:395 [inline] __qdisc_run+0x4d0/0x1640 net/sched/sch_generic.c:403 qdisc_run include/net/pkt_sched.h:120 [inline] __dev_xmit_skb net/core/dev.c:3451 [inline] __dev_queue_xmit+0x2102/0x2e00 net/core/dev.c:3807 neigh_resolve_output+0x55a/0x910 net/core/neighbour.c:1374 neigh_output include/net/neighbour.h:501 [inline] ip_finish_output2+0xd76/0x15a0 net/ipv4/ip_output.c:230 ip_finish_output+0xae9/0x10b0 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_output+0x203/0x5f0 net/ipv4/ip_output.c:406 dst_output include/net/dst.h:455 [inline] ip_local_out+0xaf/0x170 net/ipv4/ip_output.c:125 ip_send_skb+0x3e/0xe0 net/ipv4/ip_output.c:1452 udp_send_skb+0x6a4/0x1170 net/ipv4/udp.c:848 udp_sendmsg+0x1cb4/0x2550 net/ipv4/udp.c:1135 udpv6_sendmsg+0x14b2/0x2ae0 net/ipv6/udp.c:1224 inet_sendmsg+0x132/0x5a0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2227 __sys_sendmmsg+0x195/0x470 net/socket.c:2322 __do_sys_sendmmsg net/socket.c:2351 [inline] __se_sys_sendmmsg net/socket.c:2348 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2348 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f88a2e9ee99 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f88a1814168 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f88a2fb1f60 RCX: 00007f88a2e9ee99 RDX: 0000000000000001 RSI: 0000000020004d80 RDI: 0000000000000003 RBP: 00007f88a2ef8ff1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc1b6bec0f R14: 00007f88a1814300 R15: 0000000000022000 syz-executor.0 (16067) used greatest stack depth: 22152 bytes left blktrace: Concurrent blktraces are not allowed on loop7 blktrace: Concurrent blktraces are not allowed on loop7 nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based firewall rule not found. Use the iptables CT target to attach helpers instead. netlink: 4 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 1788 bytes leftover after parsing attributes in process `syz-executor.5'. caif:caif_disconnect_client(): nothing to disconnect netlink: 76 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'. netlink: 8 bytes leftover after parsing attributes in process `syz-executor.2'. x_tables: duplicate underflow at hook 2 x_tables: duplicate underflow at hook 2 netlink: 8 bytes leftover after parsing attributes in process `syz-executor.1'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 36 bytes leftover after parsing attributes in process `syz-executor.5'. netlink: 20 bytes leftover after parsing attributes in process `syz-executor.1'. netlink: 1192 bytes leftover after parsing attributes in process `syz-executor.3'. x_tables: duplicate underflow at hook 2 netlink: 76 bytes leftover after parsing attributes in process `syz-executor.1'. netlink: 16 bytes leftover after parsing attributes in process `syz-executor.1'. caif:caif_disconnect_client(): nothing to disconnect x_tables: duplicate underflow at hook 2 netlink: 48 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 48 bytes leftover after parsing attributes in process `syz-executor.0'. netlink: 48 bytes leftover after parsing attributes in process `syz-executor.0'.