syzbot

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refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 10930 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 10930 Comm: kbnepd ÒÜ'ç‘ Not tainted 6.14.0-rc5-syzkaller-00023-gbb2281fb05e5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 88 42 f5 fc 84 db 0f 85 66 ff ff ff e8 db 47 f5 fc c6 05 bf 44 86 0b 01 90 48 c7 c7 a0 14 d3 8b e8 97 76 b5 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 b8 47 f5 fc 0f b6 1d 9a 44 86 0b 31
RSP: 0018:ffffc9000502f948 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817a2229
RDX: ffff8880471b0000 RSI: ffffffff817a2236 RDI: 0000000000000001
RBP: ffff8880687a8c78 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888043555400
R13: ffff8880687a8c78 R14: ffffffff85ec13a0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c39e7b4 CR3: 000000006e100000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:275 [inline]
 __refcount_dec_and_test include/linux/refcount.h:307 [inline]
 refcount_dec_and_test include/linux/refcount.h:325 [inline]
 kref_put include/linux/kref.h:64 [inline]
 klist_dec_and_del lib/klist.c:206 [inline]
 klist_put+0x11b/0x1b0 lib/klist.c:217
 device_del+0x1d9/0x9f0 drivers/base/core.c:3831
 unregister_netdevice_many_notify+0x13aa/0x1f30 net/core/dev.c:11920
 unregister_netdevice_many net/core/dev.c:11948 [inline]
 unregister_netdevice_queue+0x307/0x3f0 net/core/dev.c:11818
 unregister_netdevice include/linux/netdevice.h:3337 [inline]
 unregister_netdev+0x1f/0x60 net/core/dev.c:11966
 bnep_session+0x21b6/0x2ca0 net/bluetooth/bnep/core.c:525
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>