------------[ 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.3.1172/10570
Modules linked in:
CPU: 1 UID: 0 PID: 10570 Comm: syz.3.1172 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 b3 8e 0b 67 48 0f b9 3a eb 4a e8 b8 21 f3 fc 48 8d 3d 51 b3 8e 0b 67 48 0f b9 3a eb 37 e8 a5 21 f3 fc 48 8d 3d 4e b3 8e 0b <67> 48 0f b9 3a eb 24 e8 92 21 f3 fc 48 8d 3d 4b b3 8e 0b 67 48 0f
RSP: 0018:ffffc90000a08c68 EFLAGS: 00010246
RAX: ffffffff84d3f25b RBX: 0000000000000003 RCX: ffff88802cba9f00
RDX: 0000000000000100 RSI: ffffffff8f3652c0 RDI: ffffffff9062a5b0
RBP: ffffc90000a08d70 R08: ffff88802cba9f00 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000100 R12: 0000000000000001
R13: 00000000ffffe3e7 R14: ffff8880327a4020 R15: ffff8880327a4168
FS:  00007f1148caf6c0(0000) GS:ffff88812504f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1148c8ed58 CR3: 000000007aefc000 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 kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:console_flush_one_record arch/x86/include/asm/irqflags.h:-1 [inline]
RIP: 0010:console_flush_all+0x7d2/0xaf0 kernel/printk/printk.c:3343
Code: ff ff e8 31 2f 21 00 90 0f 0b 90 e9 9c fc ff ff e8 23 2f 21 00 e8 3e 50 2c 0a 48 85 db 74 c0 e8 14 2f 21 00 fb 48 8b 5c 24 18 <48> 8b 44 24 28 42 80 3c 20 00 4d 8d 77 58 74 08 4c 89 f7 e8 56 c6
RSP: 0018:ffffc9000385ea80 EFLAGS: 00000293
RAX: ffffffff81a5e4ec RBX: ffffc9000385ebe0 RCX: ffff88802cba9f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000385eb90 R08: ffffffff9057a737 R09: 1ffffffff20af4e6
R10: dffffc0000000000 R11: fffffbfff20af4e7 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffffffff8f46f8a0
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
 vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 __nla_validate_parse+0x2574/0x2d50 lib/nlattr.c:647
 __nla_parse+0x40/0x60 lib/nlattr.c:732
 __nlmsg_parse include/net/netlink.h:789 [inline]
 nlmsg_parse_deprecated include/net/netlink.h:830 [inline]
 rtnl_newlink+0x20b/0x1c30 net/core/rtnetlink.c:4098
 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7112
 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: 0033:0x7f1147d9e0d9
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:00007f1148caf028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1148026090 RCX: 00007f1147d9e0d9
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000000000000026
RBP: 00007f1147e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1148026128 R14: 00007f1148026090 R15: 00007ffd719666c8
 </TASK>
----------------
Code disassembly (best guess):
   0:	54                   	push   %rsp
   1:	b3 8e                	mov    $0x8e,%bl
   3:	0b 67 48             	or     0x48(%rdi),%esp
   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 b3 8e 0b 	lea    0xb8eb351(%rip),%rdi        # 0xb8eb368
  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 b3 8e 0b 	lea    0xb8eb34e(%rip),%rdi        # 0xb8eb378
* 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 b3 8e 0b 	lea    0xb8eb34b(%rip),%rdi        # 0xb8eb388
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf