============================================
WARNING: possible recursive locking detected
6.1.140-syzkaller #0 Not tainted
--------------------------------------------
syz.3.1602/9992 is trying to acquire lock:
ffff888078008218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888078008218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3925 [inline]
ffff888078008218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300
but task is already holding lock:
ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300
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
12 locks held by syz.3.1602/9992:
#0: ffffc900001e0bc0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc1/0x670 kernel/time/timer.c:1501
#1: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#1: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#1: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x1f2/0x1510 net/ipv6/ndisc.c:484
#2: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#2: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#2: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x593/0x1590 net/ipv6/ip6_output.c:123
#3: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#3: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#3: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
#4: ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
#4: ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
#4: ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3882 [inline]
#4: ffff888076739258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x129a/0x3760 net/core/dev.c:4300
#5: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#5: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#5: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x593/0x1590 net/ipv6/ip6_output.c:123
#6: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#6: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#6: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
#7: ffff8880301707f0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
#7: ffff8880301707f0 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline]
#7: ffff8880301707f0 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmp6_send+0xb5f/0x18d0 net/ipv6/icmp.c:553
#8: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#8: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: icmp6_send+0xaa6/0x18d0 net/ipv6/icmp.c:544
#9: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#9: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#9: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: ip6_send_skb+0x10b/0x380 net/ipv6/ip6_output.c:2008
#10: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#10: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#10: ffffffff8c92ab20 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x593/0x1590 net/ipv6/ip6_output.c:123
#11: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#11: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline]
#11: ffffffff8c92ab80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x26f/0x3760 net/core/dev.c:4257
stack backtrace:
CPU: 1 PID: 9992 Comm: syz.3.1602 Not tainted 6.1.140-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
__lock_acquire+0x122f/0x7c50 kernel/locking/lockdep.c:-1
lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__dev_xmit_skb net/core/dev.c:3925 [inline]
__dev_queue_xmit+0x208f/0x3760 net/core/dev.c:4300
neigh_output include/net/neighbour.h:544 [inline]
ip6_finish_output2+0xda2/0x1590 net/ipv6/ip6_output.c:138
__ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
ip6_finish_output+0x5d3/0xa60 net/ipv6/ip6_output.c:216
ip6_send_skb+0x1d1/0x380 net/ipv6/ip6_output.c:2009
icmp6_send+0x1292/0x18d0 net/ipv6/icmp.c:632
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x37/0x4c0 net/ipv6/route.c:2827
dst_link_failure include/net/dst.h:423 [inline]
ipip6_tunnel_xmit net/ipv6/sit.c:1039 [inline]
sit_tunnel_xmit+0xaf0/0x1f60 net/ipv6/sit.c:1076
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3658 [inline]
dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674
sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
qdisc_restart net/sched/sch_generic.c:407 [inline]
__qdisc_run+0xadf/0x15f0 net/sched/sch_generic.c:415
__dev_xmit_skb net/core/dev.c:3958 [inline]
__dev_queue_xmit+0x107e/0x3760 net/core/dev.c:4300
neigh_output include/net/neighbour.h:544 [inline]
ip6_finish_output2+0xda2/0x1590 net/ipv6/ip6_output.c:138
__ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
ip6_finish_output+0x5d3/0xa60 net/ipv6/ip6_output.c:216
ip6tunnel_xmit+0x1a6/0x3a0 include/net/ip6_tunnel.h:161
ip6_tnl_xmit+0x225b/0x2ab0 net/ipv6/ip6_tunnel.c:1280
__gre6_xmit+0x960/0xc70 net/ipv6/ip6_gre.c:809
ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:865 [inline]
ip6gre_tunnel_xmit+0xf76/0x13d0 net/ipv6/ip6_gre.c:937
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3658 [inline]
dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3674
sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3895 [inline]
__dev_queue_xmit+0x18cd/0x3760 net/core/dev.c:4300
neigh_output include/net/neighbour.h:544 [inline]
ip6_finish_output2+0xda2/0x1590 net/ipv6/ip6_output.c:138
__ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
ip6_finish_output+0x5d3/0xa60 net/ipv6/ip6_output.c:216
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xbfb/0x1510 net/ipv6/ndisc.c:513
addrconf_rs_timer+0x2b8/0x600 net/ipv6/addrconf.c:3985
call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504
expire_timers kernel/time/timer.c:1549 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1820
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833
handle_softirqs+0x2a1/0x920 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:661
irq_exit_rcu+0x5/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x7b/0x290 mm/kasan/generic.c:189
Code: 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 4d 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41 80 39 00 <0f> 85 c1 01 00 00 49 ff c1 48 ff c3 75 ee e9 1c 01 00 00 44 89 cb
RSP: 0018:ffffc9000d397c98 EFLAGS: 00000246
RAX: ffffffff81dfaf01 RBX: ffffffffffffffff RCX: ffffffff81dfafb0
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88807e4e11f0
RBP: ffff88807e4e1180 R08: dffffc0000000000 R09: ffffed100fc9c23e
R10: ffffed100fc9c23f R11: 1ffff1100fc9c23e R12: ffff88802b2c6188
R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000001
instrument_atomic_read include/linux/instrumented.h:72 [inline]
atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
filp_close+0x30/0x150 fs/open.c:1424
close_files fs/file.c:422 [inline]
put_files_struct+0x1aa/0x340 fs/file.c:437
do_exit+0x8e8/0x2400 kernel/exit.c:866
do_group_exit+0x217/0x2d0 kernel/exit.c:1021
__do_sys_exit_group kernel/exit.c:1032 [inline]
__se_sys_exit_group kernel/exit.c:1030 [inline]
__x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb37e98e969
Code: Unable to access opcode bytes at 0x7fb37e98e93f.
RSP: 002b:00007ffc560478b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb37e98e969
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc5604791c R08: 00000009560479af R09: 00000000000927c0
R10: 000000000000b37c R11: 0000000000000246 R12: 00000000000001ce
R13: 00000000000927c0 R14: 0000000000050bb0 R15: 00007ffc56047970
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 48 c1 decl -0x3f(%rax)
3: eb 03 jmp 0x8
5: 4e 8d 14 3b lea (%rbx,%r15,1),%r10
9: 4d 89 d6 mov %r10,%r14
c: 4d 29 ce sub %r9,%r14
f: 49 83 fe 10 cmp $0x10,%r14
13: 7f 26 jg 0x3b
15: 4d 85 f6 test %r14,%r14
18: 0f 84 39 01 00 00 je 0x157
1e: 48 f7 d3 not %rbx
21: 4c 01 db add %r11,%rbx
24: 41 80 39 00 cmpb $0x0,(%r9)
* 28: 0f 85 c1 01 00 00 jne 0x1ef <-- trapping instruction
2e: 49 ff c1 inc %r9
31: 48 ff c3 inc %rbx
34: 75 ee jne 0x24
36: e9 1c 01 00 00 jmp 0x157
3b: 44 89 cb mov %r9d,%ebx