============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.549/8255 is trying to acquire lock:
ffff888034374f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888034374f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235
but task is already holding lock:
ffff8880243bef30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff8880243bef30 (&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
8 locks held by syz.0.549/8255:
#0: ffffc90000a08be0 ((&hsr->announce_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbe/0x5f0 kernel/time/timer.c:1745
#1: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#1: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#1: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: hsr_announce+0x83/0x360 net/hsr/hsr_device.c:419
#2: ffff8880243bef30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
#2: ffff8880243bef30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: send_hsr_supervision_frame+0x380/0xcb0 net/hsr/hsr_device.c:330
#3: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#3: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#3: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0x9e/0x2860 net/hsr/hsr_forward.c:736
#4: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#4: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline]
#4: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27b/0x3b50 net/core/dev.c:4688
#5: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#5: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#5: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x185/0x1840 net/bridge/br_device.c:52
#6: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#6: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline]
#6: ffffffff8df3d100 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27b/0x3b50 net/core/dev.c:4688
#7: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#7: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#7: ffffffff8df3d0a0 (rcu_read_lock){....}-{1:3}, at: hsr_dev_xmit+0x2d/0x360 net/hsr/hsr_device.c:229
stack backtrace:
CPU: 1 UID: 0 PID: 8255 Comm: syz.0.549 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:356 [inline]
hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235
__netdev_start_xmit include/linux/netdevice.h:5248 [inline]
netdev_start_xmit include/linux/netdevice.h:5257 [inline]
xmit_one net/core/dev.c:3845 [inline]
dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3861
__dev_queue_xmit+0x1b8d/0x3b50 net/core/dev.c:4763
dev_queue_xmit include/linux/netdevice.h:3365 [inline]
br_dev_queue_push_xmit+0x6c5/0x890 net/bridge/br_forward.c:53
NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:318
br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66
NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:318
__br_forward+0x41e/0x600 net/bridge/br_forward.c:115
deliver_clone net/bridge/br_forward.c:131 [inline]
maybe_deliver+0xb5/0x160 net/bridge/br_forward.c:191
br_flood+0x31a/0x6a0 net/bridge/br_forward.c:238
br_dev_xmit+0x11b3/0x1840 net/bridge/br_device.c:108
__netdev_start_xmit include/linux/netdevice.h:5248 [inline]
netdev_start_xmit include/linux/netdevice.h:5257 [inline]
xmit_one net/core/dev.c:3845 [inline]
dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3861
__dev_queue_xmit+0x1b8d/0x3b50 net/core/dev.c:4763
dev_queue_xmit include/linux/netdevice.h:3365 [inline]
hsr_xmit net/hsr/hsr_forward.c:438 [inline]
hsr_forward_do net/hsr/hsr_forward.c:579 [inline]
hsr_forward_skb+0x158b/0x2860 net/hsr/hsr_forward.c:741
send_hsr_supervision_frame+0x731/0xcb0 net/hsr/hsr_device.c:364
hsr_announce+0x1d5/0x360 net/hsr/hsr_device.c:421
call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x61a/0x860 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2404
handle_softirqs+0x286/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:kasan_check_range+0x1d3/0x2c0 mm/kasan/generic.c:200
Code: 4d 01 f3 49 8d 5c 24 07 4d 85 e4 49 0f 49 dc 48 83 e3 f8 49 29 dc 74 12 41 80 3b 00 0f 85 b8 00 00 00 49 ff c3 49 ff cc 75 ee <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 3e 3c 25 09 cc 45 84 ff 75 63 41
RSP: 0018:ffffc9000f22f9e8 EFLAGS: 00000256
RAX: 00007ffffffff001 RBX: 0000000000000000 RCX: ffffffff848b38e9
RDX: 0000000000000001 RSI: 0000000000000038 RDI: ffffc9000f22faa0
RBP: ffffc9000f22fc30 R08: ffffc9000f22fad7 R09: 1ffff92001e45f5a
R10: dffffc0000000000 R11: fffff52001e45f5b R12: 0000000000000007
R13: dffffc0000000000 R14: fffff52001e45f5b R15: 1ffff92001e45f54
instrument_copy_from_user_before include/linux/instrumented.h:129 [inline]
_inline_copy_from_user include/linux/uaccess.h:177 [inline]
_copy_from_user+0x69/0xb0 lib/usercopy.c:18
copy_from_user include/linux/uaccess.h:212 [inline]
copy_msghdr_from_user net/socket.c:2560 [inline]
recvmsg_copy_msghdr net/socket.c:2816 [inline]
___sys_recvmsg+0x12e/0x510 net/socket.c:2888
do_recvmmsg+0x307/0x770 net/socket.c:2987
__sys_recvmmsg net/socket.c:3061 [inline]
__do_sys_recvmmsg net/socket.c:3084 [inline]
__se_sys_recvmmsg net/socket.c:3077 [inline]
__x64_sys_recvmmsg+0x190/0x240 net/socket.c:3077
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f739578f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f73939f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f73959e6090 RCX: 00007f739578f749
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f7395813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f73959e6128 R14: 00007f73959e6090 R15: 00007f7395b0fa28
----------------
Code disassembly (best guess):
0: 4d 01 f3 add %r14,%r11
3: 49 8d 5c 24 07 lea 0x7(%r12),%rbx
8: 4d 85 e4 test %r12,%r12
b: 49 0f 49 dc cmovns %r12,%rbx
f: 48 83 e3 f8 and $0xfffffffffffffff8,%rbx
13: 49 29 dc sub %rbx,%r12
16: 74 12 je 0x2a
18: 41 80 3b 00 cmpb $0x0,(%r11)
1c: 0f 85 b8 00 00 00 jne 0xda
22: 49 ff c3 inc %r11
25: 49 ff cc dec %r12
28: 75 ee jne 0x18
* 2a: 5b pop %rbx <-- trapping instruction
2b: 41 5c pop %r12
2d: 41 5d pop %r13
2f: 41 5e pop %r14
31: 41 5f pop %r15
33: 5d pop %rbp
34: e9 3e 3c 25 09 jmp 0x9253c77
39: cc int3
3a: 45 84 ff test %r15b,%r15b
3d: 75 63 jne 0xa2
3f: 41 rex.B