============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G L
--------------------------------------------
syz.1.3475/19771 is trying to acquire lock:
ffff8880565ccfb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:347 [inline]
ffff8880565ccfb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235
but task is already holding lock:
ffff888033698fb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:347 [inline]
ffff888033698fb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: send_hsr_supervision_frame+0x380/0xcb0 net/hsr/hsr_device.c:330
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&hsr->seqnr_lock);
lock(&hsr->seqnr_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
9 locks held by syz.1.3475/19771:
#0: ffff88802a2d6ef8 (&u->iolock){+.+.}-{4:4}, at: __unix_dgram_recvmsg+0x1e2/0xd60 net/unix/af_unix.c:2570
#1: ffffc90000007ce0 ((&hsr->announce_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd4/0x640 kernel/time/timer.c:1745
#2: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#2: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#2: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: hsr_announce+0x89/0x370 net/hsr/hsr_device.c:419
#3: ffff888033698fb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:347 [inline]
#3: ffff888033698fb0 (&hsr->seqnr_lock){+.-.}-{3:3}, at: send_hsr_supervision_frame+0x380/0xcb0 net/hsr/hsr_device.c:330
#4: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#4: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#4: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0xb3/0x2860 net/hsr/hsr_forward.c:738
#5: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#5: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:903 [inline]
#5: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x277/0x3890 net/core/dev.c:4778
#6: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#6: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#6: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x193/0x1980 net/bridge/br_device.c:52
#7: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#7: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:903 [inline]
#7: ffffffff8e75e640 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x277/0x3890 net/core/dev.c:4778
#8: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#8: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#8: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: hsr_dev_xmit+0x2d/0x360 net/hsr/hsr_device.c:229
stack backtrace:
CPU: 0 UID: 0 PID: 19771 Comm: syz.1.3475 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:150 [inline]
_raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:347 [inline]
hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235
__netdev_start_xmit include/linux/netdevice.h:5325 [inline]
netdev_start_xmit include/linux/netdevice.h:5334 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2d8/0x870 net/core/dev.c:3904
__dev_queue_xmit+0x16d1/0x3890 net/core/dev.c:4854
dev_queue_xmit include/linux/netdevice.h:3385 [inline]
br_dev_queue_push_xmit+0x370/0x4a0 net/bridge/br_forward.c:53
NF_HOOK+0x360/0x3f0 include/linux/netfilter.h:318
br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66
NF_HOOK+0x360/0x3f0 include/linux/netfilter.h:318
__br_forward+0x397/0x540 net/bridge/br_forward.c:115
deliver_clone net/bridge/br_forward.c:131 [inline]
maybe_deliver net/bridge/br_forward.c:191 [inline]
br_flood+0x6ee/0xb80 net/bridge/br_forward.c:238
br_dev_xmit+0x12bd/0x1980 net/bridge/br_device.c:108
__netdev_start_xmit include/linux/netdevice.h:5325 [inline]
netdev_start_xmit include/linux/netdevice.h:5334 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2d8/0x870 net/core/dev.c:3904
__dev_queue_xmit+0x16d1/0x3890 net/core/dev.c:4854
dev_queue_xmit include/linux/netdevice.h:3385 [inline]
hsr_xmit net/hsr/hsr_forward.c:440 [inline]
hsr_forward_do net/hsr/hsr_forward.c:581 [inline]
hsr_forward_skb+0x157b/0x2860 net/hsr/hsr_forward.c:743
send_hsr_supervision_frame+0x731/0xcb0 net/hsr/hsr_device.c:364
hsr_announce+0x1db/0x370 net/hsr/hsr_device.c:421
call_timer_fn+0x192/0x640 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
handle_softirqs+0x22a/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch+0x245/0x920 kernel/sched/core.c:5155
Code: 00 00 48 85 db 0f 85 e8 01 00 00 e9 56 05 00 00 4c 8b 75 d0 49 83 c4 48 4c 89 e7 e8 15 45 1d 0a e8 10 93 38 00 fb 4c 8b 65 c0 <49> 8d bc 24 80 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90004f3f398 EFLAGS: 00000202
RAX: 0000000000006179 RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000006 RSI: ffffffff8defb8da RDI: ffffffff8c27d500
RBP: ffffc90004f3f3f0 R08: ffffffff9011d6b7 R09: 1ffffffff2023ad6
R10: dffffc0000000000 R11: fffffbfff2023ad7 R12: ffff88807eed9e80
R13: dffffc0000000000 R14: ffff888031d58000 R15: ffff8880b863b998
context_switch kernel/sched/core.c:5301 [inline]
__schedule+0x15e5/0x52d0 kernel/sched/core.c:6911
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7095
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
_raw_spin_unlock_irqrestore+0x74/0x80 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:407 [inline]
__wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:127
__unix_dgram_recvmsg+0x485/0xd60 net/unix/af_unix.c:2598
sock_recvmsg_nosec+0x10c/0x140 net/socket.c:1078
____sys_recvmsg+0x3e3/0x4a0 net/socket.c:2810
___sys_recvmsg+0x215/0x590 net/socket.c:2854
do_recvmmsg+0x334/0x800 net/socket.c:2949
__sys_recvmmsg net/socket.c:3023 [inline]
__do_sys_recvmmsg net/socket.c:3046 [inline]
__se_sys_recvmmsg net/socket.c:3039 [inline]
__x64_sys_recvmmsg+0x198/0x250 net/socket.c:3039
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ed339c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1ed4221028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f1ed3616090 RCX: 00007f1ed339c819
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007f1ed3432c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1ed3616128 R14: 00007f1ed3616090 R15: 00007f1ed373fa48
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 48 85 db test %rbx,%rbx
5: 0f 85 e8 01 00 00 jne 0x1f3
b: e9 56 05 00 00 jmp 0x566
10: 4c 8b 75 d0 mov -0x30(%rbp),%r14
14: 49 83 c4 48 add $0x48,%r12
18: 4c 89 e7 mov %r12,%rdi
1b: e8 15 45 1d 0a call 0xa1d4535
20: e8 10 93 38 00 call 0x389335
25: fb sti
26: 4c 8b 65 c0 mov -0x40(%rbp),%r12
* 2a: 49 8d bc 24 80 16 00 lea 0x1680(%r12),%rdi <-- trapping instruction
31: 00
32: 48 89 f8 mov %rdi,%rax
35: 48 c1 e8 03 shr $0x3,%rax
39: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
3e: 84 c0 test %al,%al