netdev - [syzbot] [kernel?] WARNING: refcount bug in bnep

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Message-ID: <67470620.050a0220.1286eb.0030.GAE@google.com>
Date: Wed, 27 Nov 2024 03:44:32 -0800
From: syzbot <syzbot+8b3024ae934a6e1911d9@...kaller.appspotmail.com>
To: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, rafael@...nel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [kernel?] WARNING: refcount bug in bnep_session

Hello,

syzbot found the following issue on:

HEAD commit:    fcc79e1714e8 Merge tag 'net-next-6.13' of git://git.kernel..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1216fec0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=275de99a754927af
dashboard link: https://syzkaller.appspot.com/bug?extid=8b3024ae934a6e1911d9
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1539da626e54/disk-fcc79e17.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d44dbcc68df2/vmlinux-fcc79e17.xz
kernel image: https://storage.googleapis.com/syzbot-assets/76fdad1309ae/bzImage-fcc79e17.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8b3024ae934a6e1911d9@...kaller.appspotmail.com

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 11424 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 1 UID: 0 PID: 11424 Comm: kbnepd bnep0 Not tainted 6.12.0-syzkaller-05480-gfcc79e1714e8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: e0 ec 60 8c e8 47 47 96 fc 90 0f 0b 90 90 eb 99 e8 6b 4e d5 fc c6 05 85 55 48 0b 01 90 48 c7 c7 40 ed 60 8c e8 27 47 96 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 48 4e d5 fc c6 05 5f 55 48 0b 01 90
RSP: 0018:ffffc900031877c0 EFLAGS: 00010246
RAX: f478ba731e83d900 RBX: ffff8880351dd078 RCX: ffff888069bb9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff8155fe42 R09: fffffbfff1cfa898
R10: dffffc0000000000 R11: fffffbfff1cfa898 R12: ffff8880351dd060
R13: 1ffff11006a3ba0c R14: ffff8880351dd060 R15: ffffffff85fe66a0
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc7c6bcb18 CR3: 000000000e738000 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+0x3ec/0x3f0 lib/klist.c:206
 klist_put lib/klist.c:217 [inline]
 klist_del+0xa7/0x110 lib/klist.c:230
 device_del+0x2c9/0x9b0 drivers/base/core.c:3838
 unregister_netdevice_many_notify+0x1859/0x1da0 net/core/dev.c:11556
 unregister_netdevice_many net/core/dev.c:11584 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11456
 unregister_netdevice include/linux/netdevice.h:3192 [inline]
 unregister_netdev+0x1c/0x30 net/core/dev.c:11602
 bnep_session+0x2e3c/0x3030 net/bluetooth/bnep/core.c:525
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
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