====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 Not tainted ------------------------------------------------------ syz.2.26282/28646 is trying to acquire lock: ffff88804ec48218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88804ec48218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4052 [inline] ffff88804ec48218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{3:3}, at: __dev_queue_xmit+0x334c/0x43e0 net/core/dev.c:4595 but task is already holding lock: ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4641 [inline] ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:341 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}: __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] __netif_tx_lock include/linux/netdevice.h:4641 [inline] sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:341 __dev_xmit_skb net/core/dev.c:4018 [inline] __dev_queue_xmit+0x13c7/0x43e0 net/core/dev.c:4595 dev_queue_xmit include/linux/netdevice.h:3350 [inline] neigh_resolve_output net/core/neighbour.c:1512 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1492 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0xaeb/0x2020 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] mld_sendpack+0x9e9/0x1220 net/ipv6/mcast.c:1868 mld_send_cr net/ipv6/mcast.c:2169 [inline] mld_ifc_work+0x740/0xca0 net/ipv6/mcast.c:2702 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{3:3}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __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:4052 [inline] __dev_queue_xmit+0x334c/0x43e0 net/core/dev.c:4595 dev_queue_xmit include/linux/netdevice.h:3350 [inline] neigh_resolve_output net/core/neighbour.c:1512 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1492 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0xaeb/0x2020 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] ip6_local_out+0xcd/0x4a0 net/ipv6/output_core.c:155 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1981 ip6_push_pending_frames+0xe0/0x110 net/ipv6/ip6_output.c:2002 icmpv6_push_pending_frames+0x2dc/0x460 net/ipv6/icmp.c:311 icmp6_send+0x1fa9/0x2d20 net/ipv6/icmp.c:632 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x31/0x5a0 net/ipv6/route.c:2834 dst_link_failure include/net/dst.h:429 [inline] ip_tunnel_xmit+0x2fb0/0x37b0 net/ipv4/ip_tunnel.c:865 __gre_xmit+0x8bb/0xc00 net/ipv4/ip_gre.c:488 erspan_xmit+0x56b/0x25d0 net/ipv4/ip_gre.c:747 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3776 [inline] dev_hard_start_xmit+0x93/0x740 net/core/dev.c:3792 sch_direct_xmit+0x1b2/0xcf0 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0x541/0x1bf0 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:4087 [inline] __dev_queue_xmit+0x2aa4/0x43e0 net/core/dev.c:4595 dev_queue_xmit include/linux/netdevice.h:3350 [inline] neigh_resolve_output net/core/neighbour.c:1512 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1492 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0xaeb/0x2020 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] ip6_local_out+0xcd/0x4a0 net/ipv6/output_core.c:155 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1981 udp_v6_send_skb+0x96f/0x1910 net/ipv6/udp.c:1439 udpv6_sendmsg+0x254a/0x3070 net/ipv6/udp.c:1730 inet6_sendmsg+0x105/0x140 net/ipv6/af_inet6.c:659 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] ____sys_sendmsg+0x705/0xc70 net/socket.c:2566 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620 __sys_sendmmsg+0x2f9/0x420 net/socket.c:2702 __compat_sys_sendmmsg net/compat.c:360 [inline] __do_compat_sys_sendmmsg net/compat.c:367 [inline] __se_compat_sys_sendmmsg net/compat.c:364 [inline] __ia32_compat_sys_sendmmsg+0x9d/0x100 net/compat.c:364 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#4); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2); lock(&qdisc_xmit_lock_key#4); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2); *** DEADLOCK *** 9 locks held by syz.2.26282/28646: #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: ip6_send_skb+0xb9/0x460 net/ipv6/ip6_output.c:1980 #1: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #1: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #1: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x39d/0x2020 net/ipv6/ip6_output.c:126 #2: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #2: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #2: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x276/0x43e0 net/core/dev.c:4554 #3: ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4641 [inline] #3: ffff88804a1d5158 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x3ba/0xcf0 net/sched/sch_generic.c:341 #4: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #4: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: icmp6_send+0x270/0x2d20 net/ipv6/icmp.c:477 #5: ffff88804a210998 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #5: ffff88804a210998 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline] #5: ffff88804a210998 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmp6_send+0x8d9/0x2d20 net/ipv6/icmp.c:554 #6: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #6: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: ip6_send_skb+0xb9/0x460 net/ipv6/ip6_output.c:1980 #7: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #7: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x39d/0x2020 net/ipv6/ip6_output.c:126 #8: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #8: ffffffff8e3bf3e0 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x276/0x43e0 net/core/dev.c:4554 stack backtrace: CPU: 1 UID: 0 PID: 28646 Comm: syz.2.26282 Not tainted 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 __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:4052 [inline] __dev_queue_xmit+0x334c/0x43e0 net/core/dev.c:4595 dev_queue_xmit include/linux/netdevice.h:3350 [inline] neigh_resolve_output net/core/neighbour.c:1512 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1492 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0xaeb/0x2020 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] ip6_local_out+0xcd/0x4a0 net/ipv6/output_core.c:155 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1981 ip6_push_pending_frames+0xe0/0x110 net/ipv6/ip6_output.c:2002 icmpv6_push_pending_frames+0x2dc/0x460 net/ipv6/icmp.c:311 icmp6_send+0x1fa9/0x2d20 net/ipv6/icmp.c:632 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x31/0x5a0 net/ipv6/route.c:2834 dst_link_failure include/net/dst.h:429 [inline] ip_tunnel_xmit+0x2fb0/0x37b0 net/ipv4/ip_tunnel.c:865 __gre_xmit+0x8bb/0xc00 net/ipv4/ip_gre.c:488 erspan_xmit+0x56b/0x25d0 net/ipv4/ip_gre.c:747 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3776 [inline] dev_hard_start_xmit+0x93/0x740 net/core/dev.c:3792 sch_direct_xmit+0x1b2/0xcf0 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0x541/0x1bf0 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:4087 [inline] __dev_queue_xmit+0x2aa4/0x43e0 net/core/dev.c:4595 dev_queue_xmit include/linux/netdevice.h:3350 [inline] neigh_resolve_output net/core/neighbour.c:1512 [inline] neigh_resolve_output+0x53a/0x940 net/core/neighbour.c:1492 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0xaeb/0x2020 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:215 [inline] ip6_finish_output+0x3f9/0x1360 net/ipv6/ip6_output.c:226 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip6_output+0x1f9/0x540 net/ipv6/ip6_output.c:247 dst_output include/net/dst.h:459 [inline] ip6_local_out+0xcd/0x4a0 net/ipv6/output_core.c:155 ip6_send_skb+0x112/0x460 net/ipv6/ip6_output.c:1981 udp_v6_send_skb+0x96f/0x1910 net/ipv6/udp.c:1439 udpv6_sendmsg+0x254a/0x3070 net/ipv6/udp.c:1730 inet6_sendmsg+0x105/0x140 net/ipv6/af_inet6.c:659 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] ____sys_sendmsg+0x705/0xc70 net/socket.c:2566 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620 __sys_sendmmsg+0x2f9/0x420 net/socket.c:2702 __compat_sys_sendmmsg net/compat.c:360 [inline] __do_compat_sys_sendmmsg net/compat.c:367 [inline] __se_compat_sys_sendmmsg net/compat.c:364 [inline] __ia32_compat_sys_sendmmsg+0x9d/0x100 net/compat.c:364 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/syscall_32.c:306 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f73579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f509655c EFLAGS: 00000296 ORIG_RAX: 0000000000000159 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000080007e40 RDX: 0000000000006c00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi