[syzbot] WARNING: locking bug in nilfs_find_or_create_root

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c194837ebb57 Merge branch 'for-next/core', remote-tracking..
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=1135c4ff080000
kernel config: https://syzkaller.appspot.com/x/.config?x=15a770deac0c935a
dashboard link: https://syzkaller.appspot.com/bug?extid=79cb3895126af21042fa
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=1649fcdf080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10f24cff080000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8d8ae425e7fa/disk-c194837e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c540d501ebe7/vmlinux-c194837e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+79cb38...@syzkaller.appspotmail.com

NILFS (loop0): broken superblock, retrying with spare superblock (blocksize = 1024)
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 0 PID: 3052 at kernel/locking/lockdep.c:231 check_wait_context kernel/locking/lockdep.c:4727 [inline]
WARNING: CPU: 0 PID: 3052 at kernel/locking/lockdep.c:231 __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
Modules linked in:
CPU: 0 PID: 3052 Comm: syz-executor334 Not tainted 6.0.0-rc6-syzkaller-17742-gc194837ebb57 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
pc : __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
lr : hlock_class kernel/locking/lockdep.c:231 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
sp : ffff800012763850
x29: ffff800012763930 x28: 0000000000000001 x27: ffff0000c70a3528
x26: ffff0000cb0b4300 x25: ffff0000c70a3f58 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
x20: 0000000000000000 x19: 5555560001430f3e x18: 00000000000000c0
x17: ffff80000dd0b198 x16: ffff80000db49158 x15: ffff0000c70a3500
x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
x11: ff808000081c1630 x10: ffff80000dd0b198 x9 : 4ab275c465431000
x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff800008195d30
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
Call trace:
check_wait_context kernel/locking/lockdep.c:4727 [inline]
__lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:349 [inline]
nilfs_lookup_root fs/nilfs2/the_nilfs.c:716 [inline]
nilfs_find_or_create_root+0x34/0x310 fs/nilfs2/the_nilfs.c:743
nilfs_attach_checkpoint+0x64/0x1c8 fs/nilfs2/super.c:519
nilfs_fill_super+0x154/0x2f8 fs/nilfs2/super.c:1064
nilfs_mount+0x370/0x52c fs/nilfs2/super.c:1317
legacy_get_tree+0x30/0x74 fs/fs_context.c:610
vfs_get_tree+0x40/0x140 fs/super.c:1530
do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
path_mount+0x358/0x914 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x2c4/0x3c4 fs/namespace.c:3568
__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:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190
irq event stamp: 2725
hardirqs last enabled at (2725): [<ffff800008162680>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1367 [inline]
hardirqs last enabled at (2725): [<ffff800008162680>] finish_lock_switch+0x94/0xe8 kernel/sched/core.c:4942
hardirqs last disabled at (2724): [<ffff80000bfc3cdc>] __schedule+0x84/0x5a0 kernel/sched/core.c:6393
softirqs last enabled at (2540): [<ffff8000080102e4>] _stext+0x2e4/0x37c
softirqs last disabled at (2523): [<ffff800008017c14>] ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79
---[ end trace 0000000000000000 ]---
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b8
Mem abort info:
ESR = 0x0000000096000006
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 = 0x00000006
CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000107187000
[00000000000000b8] pgd=08000001097ad003, p4d=08000001097ad003, pud=080000010b0a7003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 3052 Comm: syz-executor334 Tainted: G W 6.0.0-rc6-syzkaller-17742-gc194837ebb57 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
pc : __lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
lr : hlock_class kernel/locking/lockdep.c:231 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
sp : ffff800012763850
x29: ffff800012763930 x28: 0000000000000001 x27: ffff0000c70a3528
x26: ffff0000cb0b4300 x25: ffff0000c70a3f58 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
x20: 0000000000000000 x19: 5555560001430f3e x18: 00000000000000c0
x17: ffff80000dd0b198 x16: ffff80000db49158 x15: ffff0000c70a3500
x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
x11: ff808000081c1630 x10: ffff80000dd0b198 x9 : 0000000000040f3e
x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff800008195d30
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
Call trace:
hlock_class kernel/locking/lockdep.c:222 [inline]
check_wait_context kernel/locking/lockdep.c:4728 [inline]
__lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:349 [inline]
nilfs_lookup_root fs/nilfs2/the_nilfs.c:716 [inline]
nilfs_find_or_create_root+0x34/0x310 fs/nilfs2/the_nilfs.c:743
nilfs_attach_checkpoint+0x64/0x1c8 fs/nilfs2/super.c:519
nilfs_fill_super+0x154/0x2f8 fs/nilfs2/super.c:1064
nilfs_mount+0x370/0x52c fs/nilfs2/super.c:1317
legacy_get_tree+0x30/0x74 fs/fs_context.c:610
vfs_get_tree+0x40/0x140 fs/super.c:1530
do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
path_mount+0x358/0x914 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x2c4/0x3c4 fs/namespace.c:3568
__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:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190
Code: 9002db8a 91056210 9106614a b9400329 (3942e114)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 9002db8a adrp x10, 0x5b70000
4: 91056210 add x16, x16, #0x158
8: 9106614a add x10, x10, #0x198
c: b9400329 ldr w9, [x25]
* 10: 3942e114 ldrb w20, [x8, #184] <-- trapping instruction


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[Ryusuke Konishi]

#syz dup: BUG: unable to handle kernel paging request in kernfs_put_active

This turned out to be the same issue as the above report.

I confirmed that the associated bugfix commit "fs: fix UAF/GPF bug in
nilfs_mdt_destroy" fixes the oops.

Ryusuke Konishi