linux-kernel - [syzbot] [bluetooth?] BUG: unable to handle kernel paging request in l2cap_conn

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Message-ID: <68cef3b7.050a0220.13cd81.001e.GAE@google.com>
Date: Sat, 20 Sep 2025 11:34:31 -0700
From: syzbot <syzbot+d1bfe010cdd19081abd8@...kaller.appspotmail.com>
To: johan.hedberg@...il.com, linux-bluetooth@...r.kernel.org, 
	linux-kernel@...r.kernel.org, luiz.dentz@...il.com, marcel@...tmann.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bluetooth?] BUG: unable to handle kernel paging request in l2cap_conn_del

Hello,

syzbot found the following issue on:

HEAD commit:    8736259279a3 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=13c58534580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9ed0a6d7c80843e9
dashboard link: https://syzkaller.appspot.com/bug?extid=d1bfe010cdd19081abd8
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/025c082a7762/disk-87362592.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/606f903fe4d2/vmlinux-87362592.xz
kernel image: https://storage.googleapis.com/syzbot-assets/23ea2634f398/Image-87362592.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d1bfe010cdd19081abd8@...kaller.appspotmail.com

Unable to handle kerne
Unable to handle kernel paging request at virtual address fbd5200000000020
KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107]
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[fbd5200000000020] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 7191 Comm: syz.4.84 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : l2cap_conn_del+0x260/0x5f0 net/bluetooth/l2cap_core.c:1783
lr : l2cap_conn_del+0x354/0x5f0 net/bluetooth/l2cap_core.c:1783
sp : ffff80009d6674b0
x29: ffff80009d6674d0 x28: 0000000000000001 x27: ffff80008dcedca0
x26: ffff0000d5e18000 x25: dead000000000100 x24: 000000007ffffffe
x23: 0000000000000001 x22: ffff0000c88c1ac0 x21: dead000000000100
x20: dfff800000000000 x19: ffff0000c88c1800 x18: 00000000ffffffff
x17: ffff800093524000 x16: ffff80008b0156e8 x15: 0000000000000001
x14: 1fffe0001abc3001 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001abc3002 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 1bd5a00000000020 x7 : ffff80008312a368 x6 : 0000000000000000
x5 : 0000000000000020 x4 : ffff80009d666fb0 x3 : ffff80008a29deb8
x2 : 0000000000000001 x1 : 0000000000000002 x0 : 0000000000000001
Call trace:
 l2cap_conn_del+0x260/0x5f0 net/bluetooth/l2cap_core.c:1783 (P)
 l2cap_disconn_cfm+0x90/0xe0 net/bluetooth/l2cap_core.c:7325
 hci_disconn_cfm include/net/bluetooth/hci_core.h:2097 [inline]
 hci_conn_hash_flush+0x108/0x218 net/bluetooth/hci_conn.c:2599
 hci_dev_close_sync+0x89c/0x1154 net/bluetooth/hci_sync.c:5294
 hci_dev_do_close net/bluetooth/hci_core.c:501 [inline]
 hci_unregister_dev+0x204/0x4c0 net/bluetooth/hci_core.c:2715
 vhci_release+0x12c/0x17c drivers/bluetooth/hci_vhci.c:690
 __fput+0x340/0x75c fs/file_table.c:468
 ____fput+0x20/0x58 fs/file_table.c:496
 task_work_run+0x1dc/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x524/0x1a14 kernel/exit.c:961
 do_group_exit+0x194/0x22c kernel/exit.c:1102
 get_signal+0x11dc/0x12f8 kernel/signal.c:3034
 arch_do_signal_or_restart+0x274/0x4434 arch/arm64/kernel/signal.c:1619
 exit_to_user_mode_loop+0x7c/0x168 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:103 [inline]
 el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:745
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
Code: 54000e80 52800037 321f77f8 d343ff28 (38746908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	54000e80 	b.eq	0x1d0  // b.none
   4:	52800037 	mov	w23, #0x1                   	// #1
   8:	321f77f8 	mov	w24, #0x7ffffffe            	// #2147483646
   c:	d343ff28 	lsr	x8, x25, #3
* 10:	38746908 	ldrb	w8, [x8, x20] <-- trapping instruction


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