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

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Message-ID: <68553fc2.a00a0220.137b3.0048.GAE@google.com>
Date: Fri, 20 Jun 2025 04:02:26 -0700
From: syzbot <syzbot+59e97f6296ecdc571f71@...kaller.appspotmail.com>
To: dakr@...nel.org, gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, 
	rafael@...nel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [kernel?] BUG: unable to handle kernel paging request in netdev_unregister_kobject

Hello,

syzbot found the following issue on:

HEAD commit:    39dfc971e42d arm64/ptrace: Fix stack-out-of-bounds read in..
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=15af690c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=941e423b930a32dc
dashboard link: https://syzkaller.appspot.com/bug?extid=59e97f6296ecdc571f71
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ee1a7942f1b9/disk-39dfc971.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b94ed3d0f7e/vmlinux-39dfc971.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9ce219d3314e/Image-39dfc971.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59e97f6296ecdc571f71@...kaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff80000000000b
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff80000000000b] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 7660 Comm: kbnepd bnep0 Not tainted 6.16.0-rc1-syzkaller-g39dfc971e42d #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : klist_put lib/klist.c:212 [inline]
pc : klist_del+0x4c/0x110 lib/klist.c:230
lr : klist_del+0x28/0x110 lib/klist.c:229
sp : ffff80009e977720
x29: ffff80009e977720 x28: dfff800000000000 x27: ffff0000cda2c028
x26: 1ffff00013d2eef4 x25: ffff80009e9777a0 x24: 1fffe00019b458e5
x23: 1fffe0001ed3f28c x22: ffff0000cda2c728 x21: dfff800000000000
x20: 0000000000000000 x19: ffff0000f69f9460 x18: 00000000ffffffff
x17: ffff8000892f3474 x16: ffff800080520d04 x15: 0000000000000001
x14: 1fffe0001eb56768 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001eb56769 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 000000000000000b x7 : ffff800080c3eef0 x6 : ffff800080c3b260
x5 : ffff0000cded8998 x4 : ffff800089214348 x3 : ffff800080f87888
x2 : 0000000000000001 x1 : 0000000000000004 x0 : 0000000000000058
Call trace:
 klist_put lib/klist.c:212 [inline] (P)
 klist_del+0x4c/0x110 lib/klist.c:230 (P)
 device_del+0x234/0x808 drivers/base/core.c:3858
 netdev_unregister_kobject+0x2bc/0x3bc net/core/net-sysfs.c:2308
 unregister_netdevice_many_notify+0x1934/0x1fac net/core/dev.c:12112
 unregister_netdevice_many net/core/dev.c:12140 [inline]
 unregister_netdevice_queue net/core/dev.c:11984 [inline]
 unregister_netdevice include/linux/netdevice.h:3379 [inline]
 unregister_netdev+0x15c/0x1f8 net/core/dev.c:12158
 bnep_session+0x208c/0x223c net/bluetooth/bnep/core.c:525
 kthread+0x5fc/0x75c kernel/kthread.c:464
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
Code: f9400268 927ff914 91016280 d343fc08 (38756908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	f9400268 	ldr	x8, [x19]
   4:	927ff914 	and	x20, x8, #0xfffffffffffffffe
   8:	91016280 	add	x0, x20, #0x58
   c:	d343fc08 	lsr	x8, x0, #3
* 10:	38756908 	ldrb	w8, [x8, x21] <-- trapping instruction


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