------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 7990 at lib/refcount.c:25 refcount_warn_saturate+0xff/0x1a0 lib/refcount.c:25
Modules linked in:
CPU: 0 PID: 7990 Comm: syz.5.996 Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:refcount_warn_saturate+0xff/0x1a0 lib/refcount.c:25
Code: 09 01 48 c7 c7 40 6b 59 8a e8 dd 27 bb 05 0f 0b eb e0 e8 04 42 9c fd c6 05 ae 8f 79 09 01 48 c7 c7 80 6a 59 8a e8 c1 27 bb 05 <0f> 0b eb c4 e8 e8 41 9c fd c6 05 93 8f 79 09 01 48 c7 c7 e0 6a 59
RSP: 0018:ffffc90000007848 EFLAGS: 00010246
RAX: e4dc74cef56f3300 RBX: 0000000000000002 RCX: ffff88802c02d940
RDX: 0000000000000100 RSI: 0000000080000101 RDI: 0000000000000000
RBP: ffffc900000079b0 R08: dffffc0000000000 R09: fffff52000000e6d
R10: fffff52000000e6d R11: 1ffff92000000e6c R12: ffff88807b161a80
R13: dffffc0000000000 R14: 0000000000000002 R15: 0000000000000000
FS:  00007fb37bb686c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000005000 CR3: 0000000022bde000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 get_net include/net/net_namespace.h:252 [inline]
 tipc_aead_encrypt net/tipc/crypto.c:832 [inline]
 tipc_crypto_xmit+0x1949/0x2560 net/tipc/crypto.c:1772
 tipc_bearer_xmit_skb+0x228/0x3c0 net/tipc/bearer.c:574
 tipc_disc_timeout+0x568/0x6b0 net/tipc/discover.c:338
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4785
Code: be ff ff ff ff e8 2c 0e 4e 08 85 c0 74 4a 4d 85 ff 75 66 e9 fe 00 00 00 48 89 df e8 26 6a 57 08 e8 21 7f 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 99 10 fe ff 43 80 3c
RSP: 0018:ffffc9000338f708 EFLAGS: 00000282
RAX: e4dc74cef56f3300 RBX: ffff8880b903a300 RCX: e4dc74cef56f3300
RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: ffffffff8a59a740
RBP: 1ffff1101720760b R08: dffffc0000000000 R09: ffffed1017207461
R10: ffffed1017207461 R11: 1ffff11017207460 R12: ffff8880b903b048
R13: dffffc0000000000 R14: ffff8880b903adc8 R15: 0000000000000000
 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4902
 context_switch kernel/sched/core.c:5033 [inline]
 __schedule+0x11c0/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 snd_rawmidi_write+0x3e3/0xbc0 sound/core/rawmidi.c:1542
 do_loop_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x3e4/0x7b0 fs/read_write.c:857
 vfs_writev fs/read_write.c:928 [inline]
 do_writev+0x254/0x410 fs/read_write.c:971
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb37dd00929
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:00007fb37bb68038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fb37df27fa0 RCX: 00007fb37dd00929
RDX: 0000000000000002 RSI: 0000200000000840 RDI: 0000000000000009
RBP: 00007fb37dd82b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb37df27fa0 R15: 00007ffc317402e8
 </TASK>
----------------
Code disassembly (best guess):
   0:	be ff ff ff ff       	mov    $0xffffffff,%esi
   5:	e8 2c 0e 4e 08       	call   0x84e0e36
   a:	85 c0                	test   %eax,%eax
   c:	74 4a                	je     0x58
   e:	4d 85 ff             	test   %r15,%r15
  11:	75 66                	jne    0x79
  13:	e9 fe 00 00 00       	jmp    0x116
  18:	48 89 df             	mov    %rbx,%rdi
  1b:	e8 26 6a 57 08       	call   0x8576a46
  20:	e8 21 7f 2a 00       	call   0x2a7f46
  25:	fb                   	sti
  26:	48 83 c4 08          	add    $0x8,%rsp
* 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:	c3                   	ret
  35:	48 89 df             	mov    %rbx,%rdi
  38:	e8 99 10 fe ff       	call   0xfffe10d6
  3d:	43                   	rex.XB
  3e:	80                   	.byte 0x80
  3f:	3c                   	.byte 0x3c