============================================ WARNING: possible recursive locking detected 6.8.0-rc4-syzkaller-00014-g7e90b5c295ec #0 Not tainted -------------------------------------------- syz-executor.0/5476 is trying to acquire lock: ffff8880329c6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880329c6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3806 [inline] ffff8880329c6218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x2f94/0x3ee0 net/core/dev.c:4317 but task is already holding lock: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:192 [inline] ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3763 [inline] ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1090/0x3ee0 net/core/dev.c:4317 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** May be due to missing lock nesting notation 8 locks held by syz-executor.0/5476: #0: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #0: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #0: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x364/0x2550 net/ipv4/ip_output.c:228 #1: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #1: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #1: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3ee0 net/core/dev.c:4276 #2: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #2: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #2: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x109/0x1740 net/bridge/br_device.c:44 #3: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #3: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #3: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3ee0 net/core/dev.c:4276 #4: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #4: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #4: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:192 [inline] #4: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3763 [inline] #4: ffff8880658b2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1090/0x3ee0 net/core/dev.c:4317 #5: ffff88802e63e0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #5: ffff88802e63e0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline] #5: ffff88802e63e0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x337/0xc20 net/sched/sch_generic.c:340 #6: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #6: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #6: ffffffff8d7ad160 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x364/0x2550 net/ipv4/ip_output.c:228 #7: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #7: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #7: ffffffff8d7ad100 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3ee0 net/core/dev.c:4276 stack backtrace: CPU: 0 PID: 5476 Comm: syz-executor.0 Not tainted 6.8.0-rc4-syzkaller-00014-g7e90b5c295ec #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3856 [inline] __lock_acquire+0x2111/0x3b40 kernel/locking/lockdep.c:5137 lock_acquire kernel/locking/lockdep.c:5754 [inline] lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:3806 [inline] __dev_queue_xmit+0x2f94/0x3ee0 net/core/dev.c:4317 dev_queue_xmit include/linux/netdevice.h:3171 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x169f/0x2550 net/ipv4/ip_output.c:235 __ip_finish_output net/ipv4/ip_output.c:313 [inline] __ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:295 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433 dst_output include/net/dst.h:451 [inline] ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:129 iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1dbc/0x33d0 net/ipv4/ip_tunnel.c:831 erspan_xmit+0x523/0x1bf0 net/ipv4/ip_gre.c:720 __netdev_start_xmit include/linux/netdevice.h:4989 [inline] netdev_start_xmit include/linux/netdevice.h:5003 [inline] xmit_one net/core/dev.c:3547 [inline] dev_hard_start_xmit+0x13a/0x6d0 net/core/dev.c:3563 sch_direct_xmit+0x1ac/0xc20 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3776 [inline] __dev_queue_xmit+0x12b4/0x3ee0 net/core/dev.c:4317 dev_queue_xmit include/linux/netdevice.h:3171 [inline] br_dev_queue_push_xmit+0x272/0x7c0 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] br_forward_finish+0xf5/0x130 net/bridge/br_forward.c:66 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] __br_forward+0x1e5/0x5b0 net/bridge/br_forward.c:115 deliver_clone+0x5b/0xa0 net/bridge/br_forward.c:131 maybe_deliver+0x31a/0x3e0 net/bridge/br_forward.c:190 br_flood+0x17e/0x5c0 net/bridge/br_forward.c:236 br_dev_xmit+0xf05/0x1740 net/bridge/br_device.c:84 __netdev_start_xmit include/linux/netdevice.h:4989 [inline] netdev_start_xmit include/linux/netdevice.h:5003 [inline] xmit_one net/core/dev.c:3547 [inline] dev_hard_start_xmit+0x13a/0x6d0 net/core/dev.c:3563 __dev_queue_xmit+0x7b6/0x3ee0 net/core/dev.c:4351 dev_queue_xmit include/linux/netdevice.h:3171 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x169f/0x2550 net/ipv4/ip_output.c:235 __ip_finish_output net/ipv4/ip_output.c:313 [inline] __ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:295 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_mc_output+0x1dd/0x6a0 net/ipv4/ip_output.c:420 dst_output include/net/dst.h:451 [inline] dst_output include/net/dst.h:449 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] ip_send_skb+0x326/0x560 net/ipv4/ip_output.c:1489 udp_send_skb+0x73f/0x1530 net/ipv4/udp.c:963 udp_sendmsg+0x1a36/0x2b40 net/ipv4/udp.c:1250 inet_sendmsg+0x105/0x140 net/ipv4/af_inet.c:850 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0xa09/0xc90 net/socket.c:2584 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2638 __sys_sendmmsg+0x1a1/0x450 net/socket.c:2724 __do_sys_sendmmsg net/socket.c:2753 [inline] __se_sys_sendmmsg net/socket.c:2750 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2750 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7f5737c7dda9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f57389160c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f5737dabf80 RCX: 00007f5737c7dda9 RDX: 00000000000001f4 RSI: 0000000020000740 RDI: 0000000000000003 RBP: 00007f5737cca47a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f5737dabf80 R15: 00007ffe93b82118