------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#1: syz.7.9155/5597
Modules linked in:
CPU: 1 UID: 0 PID: 5597 Comm: syz.7.9155 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: 54 b8 8e 0b 67 48 0f b9 3a eb 4a e8 b8 21 f3 fc 48 8d 3d 51 b8 8e 0b 67 48 0f b9 3a eb 37 e8 a5 21 f3 fc 48 8d 3d 4e b8 8e 0b <67> 48 0f b9 3a eb 24 e8 92 21 f3 fc 48 8d 3d 4b b8 8e 0b 67 48 0f
RSP: 0018:ffffc90000a08ca8 EFLAGS: 00010246
RAX: ffffffff84d3f25b RBX: 0000000000000003 RCX: ffff8880645bdd00
RDX: 0000000000000100 RSI: ffffffff8f3652c0 RDI: ffffffff9062aab0
RBP: ffffc90000a08db0 R08: ffff8880645bdd00 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000000001
R13: 000000010001a003 R14: ffff888027b50820 R15: ffff888027b50968
FS:  00007f8cfb3b36c0(0000) GS:ffff88812504f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f67dd5de77c CR3: 0000000029aea000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 do_softirq+0x76/0xd0 kernel/softirq.c:523
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
 netdev_for_each_tx_queue include/linux/netdevice.h:2741 [inline]
 dev_deactivate_many+0x778/0xda0 net/sched/sch_generic.c:1394
 __dev_close_many+0x180/0x6e0 net/core/dev.c:1786
 __dev_close net/core/dev.c:1815 [inline]
 __dev_change_flags+0x3f5/0x820 net/core/dev.c:9787
 netif_change_flags+0x7c/0x1b0 net/core/dev.c:9854
 do_setlink+0xdd6/0x4670 net/core/rtnetlink.c:3266
 rtnl_group_changelink net/core/rtnetlink.c:3919 [inline]
 __rtnl_newlink net/core/rtnetlink.c:4085 [inline]
 rtnl_newlink+0x146f/0x1c30 net/core/rtnetlink.c:4215
 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7132
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8cfa59e0d9
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:00007f8cfb3b3028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8cfa825fa0 RCX: 00007f8cfa59e0d9
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007f8cfa635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8cfa826038 R14: 00007f8cfa825fa0 R15: 00007ffd50862838
 </TASK>
----------------
Code disassembly (best guess):
   0:	54                   	push   %rsp
   1:	b8 8e 0b 67 48       	mov    $0x48670b8e,%eax
   6:	0f b9 3a             	ud1    (%rdx),%edi
   9:	eb 4a                	jmp    0x55
   b:	e8 b8 21 f3 fc       	call   0xfcf321c8
  10:	48 8d 3d 51 b8 8e 0b 	lea    0xb8eb851(%rip),%rdi        # 0xb8eb868
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 a5 21 f3 fc       	call   0xfcf321c8
  23:	48 8d 3d 4e b8 8e 0b 	lea    0xb8eb84e(%rip),%rdi        # 0xb8eb878
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 92 21 f3 fc       	call   0xfcf321c8
  36:	48 8d 3d 4b b8 8e 0b 	lea    0xb8eb84b(%rip),%rdi        # 0xb8eb888
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf