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

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Message-ID: <000000000000cbade405ee5c318c@google.com>
Date:   Sat, 26 Nov 2022 01:23:43 -0800
From:   syzbot <syzbot+7bddaf6b35765f4a1bd3@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] BUG: unable to handle kernel paging request in __detach_mounts

Hello,

syzbot found the following issue on:

HEAD commit:    6d464646530f 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=13016e75880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=23eec5c79c22aaf8
dashboard link: https://syzkaller.appspot.com/bug?extid=7bddaf6b35765f4a1bd3
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
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=123594e3880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=164dd7e5880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f22d29413625/disk-6d464646.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/389f0a5f1a4a/vmlinux-6d464646.xz
kernel image: https://storage.googleapis.com/syzbot-assets/48ddb02d82da/Image-6d464646.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/ff775172773d/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7bddaf6b35765f4a1bd3@...kaller.appspotmail.com

Unable to handle kernel paging request at virtual address 000fbcb9763f43bd
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
  CM = 0, WnR = 0
[000fbcb9763f43bd] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 3084 Comm: syz-executor274 Not tainted 6.1.0-rc6-syzkaller-32662-g6d464646530f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : lookup_mountpoint fs/namespace.c:768 [inline]
pc : __detach_mounts+0xcc/0x3c4 fs/namespace.c:1741
lr : lookup_mountpoint fs/namespace.c:767 [inline]
lr : __detach_mounts+0xe4/0x3c4 fs/namespace.c:1741
sp : ffff80000ffbbcc0
x29: ffff80000ffbbcc0 x28: ffff0000c63e8000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000001
x23: ffff80000c0f4540 x22: ffff0000c0555618 x21: 4a0fbcb9763f43ad
x20: ffff8000085d7f60 x19: ffff80000d300700 x18: 00000000000000c0
x17: ffff80000dda8198 x16: ffff80000dbe6158 x15: ffff0000c63e8000
x14: ffff80000dda8198 x13: ffff80000dbe6158 x12: ffff0000c63e8000
x11: ff80800008607f5c x10: 0000000000000000 x9 : ffff800008607f5c
x8 : ffff0000c63e8000 x7 : ffff8000085d7f60 x6 : 0000000000000000
x5 : 0000000000000020 x4 : ffff80000ffbbaa0 x3 : 0000000000000000
x2 : ffff8000081a6214 x1 : ffff80000cbaab30 x0 : 0000000000000000
Call trace:
 lookup_mountpoint fs/namespace.c:767 [inline]
 __detach_mounts+0xcc/0x3c4 fs/namespace.c:1741
 detach_mounts fs/mount.h:116 [inline]
 vfs_rmdir+0x25c/0x264 fs/namei.c:4127
 do_rmdir+0x164/0x2a4 fs/namei.c:4181
 __do_sys_unlinkat fs/namei.c:4361 [inline]
 __se_sys_unlinkat fs/namei.c:4355 [inline]
 __arm64_sys_unlinkat+0x90/0xa8 fs/namei.c:4355
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584
Code: 0b080128 8a0b0108 f8687955 b4000115 (f9400aa8) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	0b080128 	add	w8, w9, w8
   4:	8a0b0108 	and	x8, x8, x11
   8:	f8687955 	ldr	x21, [x10, x8, lsl #3]
   c:	b4000115 	cbz	x21, 0x2c
* 10:	f9400aa8 	ldr	x8, [x21, #16] <-- trapping instruction


---
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