BUG: unable to handle kernel NULL pointer dereference in fuse_dev_release

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 247f34f7b803 Linux 6.1-rc2
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=123e65a8480000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa9bed8d6a8992a0
dashboard link: https://syzkaller.appspot.com/bug?extid=7f8d6161254f65339fbb
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org mik...@szeredi.hu]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/05f9a7fca332/disk-247f34f7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ec50c3ad7d48/vmlinux-247f34f7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1446f94b11ed/Image-247f34f7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7f8d61...@syzkaller.appspotmail.com

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
Mem abort info:
ESR = 0x0000000096000046
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000046
CM = 0, WnR = 1
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000143267000
[0000000000000008] pgd=0800000145203003, p4d=0800000145203003, pud=080000013eea4003, pmd=0000000000000000
Internal error: Oops: 0000000096000046 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 9886 Comm: syz-executor.3 Not tainted 6.1.0-rc2-syzkaller-154433-g247f34f7b803 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __list_splice include/linux/list.h:449 [inline]
pc : list_splice_init include/linux/list.h:491 [inline]
pc : fuse_dev_release+0x90/0x24c fs/fuse/dev.c:2207
lr : list_splice_init include/linux/list.h:491 [inline]
lr : fuse_dev_release+0x88/0x24c fs/fuse/dev.c:2207
sp : ffff800016a6bce0
x29: ffff800016a6bd00 x28: 00000000000e001b x27: 0000000000002000
x26: ffff0000c1697af8 x25: 0000000000000000 x24: ffff000103124ff0
x23: ffff800016a6bce8 x22: 0000000000000ff0 x21: ffff0000fed7e210
x20: ffff0000fe2f0400 x19: ffff0000fed7e200 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000003 x12: ffff80000d3bb3b0
x11: ff80800008cd572c x10: 0000000000000000 x9 : 0000000000000000
x8 : ffff0000fe939340 x7 : 0000000000000000 x6 : ffff800008cd56f8
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
__list_splice include/linux/list.h:447 [inline]
list_splice_init include/linux/list.h:491 [inline]
fuse_dev_release+0x90/0x24c fs/fuse/dev.c:2207
__fput+0x198/0x3e4 fs/file_table.c:320
____fput+0x20/0x30 fs/file_table.c:348
task_work_run+0x100/0x148 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
Code: 540001a0 97d7467a f94007e8 f9400709 (f9000737)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 540001a0 b.eq 0x34 // b.none
4: 97d7467a bl 0xffffffffff5d19ec
8: f94007e8 ldr x8, [sp, #8]
c: f9400709 ldr x9, [x24, #8]
* 10: f9000737 str x23, [x25, #8] <-- trapping instruction


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.