====================================================== WARNING: possible circular locking dependency detected 6.1.73-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.5/7008 is trying to acquire lock: ffff0000c3825218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000c3825218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3884 [inline] ffff0000c3825218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1e3c/0x38d8 net/core/dev.c:4259 but task is already holding lock: ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (_xmit_ETHER#2){+.-.}-{2:2}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] __netif_tx_lock include/linux/netdevice.h:4304 [inline] sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3854 [inline] __dev_queue_xmit+0x1658/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] lapbeth_data_transmit+0x1e0/0x298 drivers/net/wan/lapbether.c:259 lapb_data_transmit+0x8c/0xb0 net/lapb/lapb_iface.c:447 lapb_transmit_buffer+0x178/0x204 net/lapb/lapb_out.c:149 lapb_send_control+0x220/0x320 net/lapb/lapb_subr.c:251 lapb_establish_data_link+0x94/0xec lapb_device_event+0x348/0x4e0 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455 __dev_notify_flags+0x2ac/0x534 dev_change_flags+0xc8/0x154 net/core/dev.c:8658 devinet_ioctl+0x858/0x17e4 net/ipv4/devinet.c:1146 inet_ioctl+0x2ac/0x4d8 net/ipv4/af_inet.c:1003 sock_do_ioctl+0x134/0x2dc net/socket.c:1204 sock_ioctl+0x4ec/0x858 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #0 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x1e3c/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1556 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xc38/0x179c net/ipv6/ndisc.c:509 ndisc_solicit+0x3ac/0x590 neigh_probe+0xc4/0x128 net/core/neighbour.c:1068 __neigh_event_send+0xe50/0x1668 net/core/neighbour.c:1235 neigh_event_send_probe include/net/neighbour.h:468 [inline] neigh_event_send include/net/neighbour.h:474 [inline] neigh_resolve_output+0x17c/0x618 net/core/neighbour.c:1540 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161 ip6_send_skb+0x118/0x428 net/ipv6/ip6_output.c:1995 ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:2015 icmpv6_push_pending_frames+0x288/0x3f4 net/ipv6/icmp.c:303 icmp6_send+0x11a8/0x1b2c net/ipv6/icmp.c:622 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2789 dst_link_failure+0x11c/0x160 include/net/dst.h:423 ip_tunnel_xmit+0x1e1c/0x28f4 net/ipv4/ip_tunnel.c:819 __gre_xmit net/ipv4/ip_gre.c:469 [inline] erspan_xmit+0x9c8/0x1498 net/ipv4/ip_gre.c:718 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3900 [inline] __dev_queue_xmit+0x1758/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1556 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] rawv6_send_hdrinc+0xd74/0x1bfc net/ipv6/raw.c:654 rawv6_sendmsg+0x1114/0x1bc0 net/ipv6/raw.c:912 inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:836 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x55c/0x848 net/socket.c:2514 ___sys_sendmsg net/socket.c:2568 [inline] __sys_sendmmsg+0x318/0x7d8 net/socket.c:2654 __do_sys_sendmmsg net/socket.c:2683 [inline] __se_sys_sendmmsg net/socket.c:2680 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2680 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 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 *** 10 locks held by syz-executor.5/7008: #0: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #1: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #2: ffff8000159f4d40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 #3: ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #3: ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] #3: ffff0000d296d4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 #4: ffff0000d5e700b0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:360 [inline] #4: ffff0000d5e700b0 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmpv6_xmit_lock+0xec/0x19c net/ipv6/icmp.c:108 #5: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #6: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #7: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #8: ffff8000159f4ce0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:305 #9: ffff8000159f4d40 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:305 stack backtrace: CPU: 0 PID: 7008 Comm: syz-executor.5 Not tainted 6.1.73-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2048 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x1e3c/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1556 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xc38/0x179c net/ipv6/ndisc.c:509 ndisc_solicit+0x3ac/0x590 neigh_probe+0xc4/0x128 net/core/neighbour.c:1068 __neigh_event_send+0xe50/0x1668 net/core/neighbour.c:1235 neigh_event_send_probe include/net/neighbour.h:468 [inline] neigh_event_send include/net/neighbour.h:474 [inline] neigh_resolve_output+0x17c/0x618 net/core/neighbour.c:1540 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161 ip6_send_skb+0x118/0x428 net/ipv6/ip6_output.c:1995 ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:2015 icmpv6_push_pending_frames+0x288/0x3f4 net/ipv6/icmp.c:303 icmp6_send+0x11a8/0x1b2c net/ipv6/icmp.c:622 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2789 dst_link_failure+0x11c/0x160 include/net/dst.h:423 ip_tunnel_xmit+0x1e1c/0x28f4 net/ipv4/ip_tunnel.c:819 __gre_xmit net/ipv4/ip_gre.c:469 [inline] erspan_xmit+0x9c8/0x1498 net/ipv4/ip_gre.c:718 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3900 [inline] __dev_queue_xmit+0x1758/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x518/0x618 net/core/neighbour.c:1556 neigh_output include/net/neighbour.h:544 [inline] ip6_finish_output2+0xdac/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] rawv6_send_hdrinc+0xd74/0x1bfc net/ipv6/raw.c:654 rawv6_sendmsg+0x1114/0x1bc0 net/ipv6/raw.c:912 inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:836 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x55c/0x848 net/socket.c:2514 ___sys_sendmsg net/socket.c:2568 [inline] __sys_sendmmsg+0x318/0x7d8 net/socket.c:2654 __do_sys_sendmmsg net/socket.c:2683 [inline] __se_sys_sendmmsg net/socket.c:2680 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2680 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585