syzbot

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refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 17378 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 17378 Comm: kbnepd bnep0 Not tainted 6.15.0-syzkaller-12058-g64980441d269 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28
Code: 00 65 e1 8b e8 87 ef c9 fc 90 0f 0b 90 90 eb d7 e8 1b 41 06 fd c6 05 f8 cb cf 0a 01 90 48 c7 c7 60 65 e1 8b e8 67 ef c9 fc 90 <0f> 0b 90 90 eb b7 e8 fb 40 06 fd c6 05 d5 cb cf 0a 01 90 48 c7 c7
RSP: 0018:ffffc9000c8276a0 EFLAGS: 00010246
RAX: 6caad8d84d128900 RBX: 0000000000000003 RCX: ffff88803105bc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa44 R12: dffffc0000000000
R13: ffff88805b80d460 R14: ffff88805b80d478 R15: ffffffff85ef1a70
FS:  0000000000000000(0000) GS:ffff888125c89000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f59c96e7d60 CR3: 0000000033e86000 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:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 kref_put include/linux/kref.h:64 [inline]
 klist_dec_and_del+0x3c7/0x3d0 lib/klist.c:206
 klist_put lib/klist.c:217 [inline]
 klist_del+0xa6/0x110 lib/klist.c:230
 device_del+0x280/0x8e0 drivers/base/core.c:3858
 unregister_netdevice_many_notify+0x1d52/0x2320 net/core/dev.c:12111
 unregister_netdevice_many net/core/dev.c:12139 [inline]
 unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:11983
 unregister_netdevice include/linux/netdevice.h:3379 [inline]
 unregister_netdev+0x1f/0x60 net/core/dev.c:12157
 bnep_session+0x294d/0x2b40 net/bluetooth/bnep/core.c:525
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>