syzbot

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refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 9001 at lib/refcount.c:25 refcount_warn_saturate+0xff/0x1a0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 9001 Comm: syz.0.1025 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
vkms_vblank_simulate: vblank timer overrun
RSP: 0018:ffffc90000dd06a8 EFLAGS: 00010246
RAX: 6698ed0737da4f00 RBX: 0000000000000002 RCX: ffff888025e9d940
RDX: 0000000000000100 RSI: 0000000000000101 RDI: 0000000000000000
RBP: ffffc90000dd0808 R08: dffffc0000000000 R09: fffff520001ba039
R10: fffff520001ba039 R11: 1ffff920001ba038 R12: ffff888079129a80
R13: dffffc0000000000 R14: 0000000000000002 R15: 0000000000000000
FS:  00007f0a313f76c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3001fffc CR3: 000000006673b000 CR4: 00000000003506e0
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_crypto_clone_msg+0x91/0x160 net/tipc/crypto.c:1667
 tipc_crypto_xmit+0x1ac5/0x2560 net/tipc/crypto.c:1728
 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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: f6 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 8e 9a b1 f7 48 89 df e8 56 6f b2 f7 e8 a1 13 d3 f7 fb bf 01 00 00 00 <e8> 86 93 a6 f7 65 8b 05 27 a3 57 76 85 c0 74 02 5b c3 e8 d4 ad 55
RSP: 0018:ffffc9000344f7f0 EFLAGS: 00000286
RAX: 6698ed0737da4f00 RBX: ffff888076663518 RCX: 6698ed0737da4f00
RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: 0000000000000001
RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed100eccc6a4
R10: ffffed100eccc6a4 R11: 1ffff1100eccc6a3 R12: 00fff00000080017
R13: 0000000000000000 R14: ffff888076663510 R15: ffff888076663518
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 delete_from_page_cache+0x129/0x190 mm/filemap.c:267
 truncate_inode_page+0x8d/0xb0 mm/truncate.c:219
 shmem_undo_range+0x49b/0x1840 mm/shmem.c:960
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x20d/0xa00 mm/shmem.c:1145
 evict+0x485/0x870 fs/inode.c:647
 __dentry_kill+0x431/0x650 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5ee/0x930 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0a3358e58a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 43 91 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 a3 91 02 00 8b 44 24
RSP: 002b:00007f0a313f6e00 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00000000ffffffff RCX: 00007f0a3358e58a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000002 R08: 0000000000000000 R09: 000000000000441b
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 00007f0a313f6ef0 R14: 00007f0a313f6eb0 R15: 00007f0a28fd7000
 </TASK>
----------------
Code disassembly (best guess):
   0:	f6 ff                	idiv   %bh
   2:	0f 1f 00             	nopl   (%rax)
   5:	53                   	push   %rbx
   6:	48 89 fb             	mov    %rdi,%rbx
   9:	48 83 c7 18          	add    $0x18,%rdi
   d:	48 8b 74 24 08       	mov    0x8(%rsp),%rsi
  12:	e8 8e 9a b1 f7       	call   0xf7b19aa5
  17:	48 89 df             	mov    %rbx,%rdi
  1a:	e8 56 6f b2 f7       	call   0xf7b26f75
  1f:	e8 a1 13 d3 f7       	call   0xf7d313c5
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 86 93 a6 f7       	call   0xf7a693b5 <-- trapping instruction
  2f:	65 8b 05 27 a3 57 76 	mov    %gs:0x7657a327(%rip),%eax        # 0x7657a35d
  36:	85 c0                	test   %eax,%eax
  38:	74 02                	je     0x3c
  3a:	5b                   	pop    %rbx
  3b:	c3                   	ret
  3c:	e8                   	.byte 0xe8
  3d:	d4                   	(bad)
  3e:	ad                   	lods   %ds:(%rsi),%eax
  3f:	55                   	push   %rbp