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From:   Ryusuke Konishi <konishi.ryusuke@gmail.com>
Date:   Tue, 18 Oct 2022 09:50:05 +0900
Message-ID: <CAKFNMomSc0s0fWzQHO0uJxsmx0PtXCgUqDZVvW0uA+Yt72GwDg@mail.gmail.com>
Subject: Re: [syzbot] BUG: spinlock bad magic in nilfs_palloc_destroy_cache
To:     syzbot <syzbot+5f89bb8d098de14e095a@syzkaller.appspotmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-nilfs@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
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On Mon, Oct 17, 2022 at 4:53 PM syzbot  wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    bbed346d5a96 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=14b7bfa4880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
> dashboard link: https://syzkaller.appspot.com/bug?extid=5f89bb8d098de14e095a
> 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=16dbead6880000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=105d329a880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/79de466a501c/mount_0.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5f89bb8d098de14e095a@syzkaller.appspotmail.com
>
> BUG: spinlock bad magic on CPU#1, syz-executor283/3079
>  lock: lock_classes+0x4aac0/0x180000, .magic: ffff8000, .owner: /235063856, .owner_cpu: 242347152
> CPU: 1 PID: 3079 Comm: syz-executor283 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
> Call trace:
>  dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
>  show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
>  dump_stack+0x1c/0x58 lib/dump_stack.c:113
>  spin_dump kernel/locking/spinlock_debug.c:69 [inline]
>  spin_bug+0xa8/0xec kernel/locking/spinlock_debug.c:77
>  debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline]
>  do_raw_spin_lock+0xb0/0x110 kernel/locking/spinlock_debug.c:114
>  __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
>  _raw_spin_lock+0x5c/0x6c kernel/locking/spinlock.c:154
>  spin_lock include/linux/spinlock.h:349 [inline]
>  nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
>  nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
>  nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
>  nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
>  nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
>  evict+0xec/0x334 fs/inode.c:665
>  iput_final fs/inode.c:1748 [inline]
>  iput+0x2c4/0x324 fs/inode.c:1774
>  nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
>  generic_shutdown_super+0x8c/0x190 fs/super.c:491
>  kill_block_super+0x30/0x78 fs/super.c:1427
>  deactivate_locked_super+0x70/0xe8 fs/super.c:332
>  deactivate_super+0xd0/0xd4 fs/super.c:363
>  cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
>  __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
>  task_work_run+0xc4/0x14c kernel/task_work.c:177
>  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
> Unable to handle kernel paging request at virtual address ffff80000d272a70
> Mem abort info:
>   ESR = 0x0000000096000047
>   EC = 0x25: DABT (current EL), IL = 32 bits
>   SET = 0, FnV = 0
>   EA = 0, S1PTW = 0
>   FSC = 0x07: level 3 translation fault
> Data abort info:
>   ISV = 0, ISS = 0x00000047
>   CM = 0, WnR = 1
> swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000001c566b000
> [ffff80000d272a70] pgd=100000023ffff003, p4d=100000023ffff003, pud=100000023fffe003, pmd=100000023fffa003, pte=0000000000000000
> Internal error: Oops: 0000000096000047 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 1 PID: 3079 Comm: syz-executor283 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
> pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : queued_spin_lock_slowpath+0x198/0x380 kernel/locking/qspinlock.c:474
> lr : queued_spin_lock_slowpath+0x114/0x380 kernel/locking/qspinlock.c:405
> sp : ffff800010fe3a70
> x29: ffff800010fe3a70 x28: ffff0000c02f4f80 x27: 0000000000000000
> x26: ffff80000d30cf28 x25: 0000000000000000 x24: ffff0001fefefa40
> x23: 0000000000000000 x22: ffff80000d30cf28 x21: ffff80000d272a40
> x20: 0000000000000001 x19: ffff80000db93c18 x18: 0000000000000260
> x17: 6e69676e45206574 x16: 0000000000000002 x15: 0000000000000000
> x14: 0000000000000000 x13: 0000000000000db7 x12: 0000000000000000
> x11: ffff80000d272a70 x10: 0000000000080000 x9 : ffff0001fefefa48
> x8 : ffff0001fefefa40 x7 : 205b5d3838383531 x6 : ffff80000819545c
> x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
> x2 : 0000000000000001 x1 : ffff80000ce26a9f x0 : 0000000000000001
> Call trace:
>  decode_tail kernel/locking/qspinlock.c:131 [inline]
>  queued_spin_lock_slowpath+0x198/0x380 kernel/locking/qspinlock.c:471
>  queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
>  do_raw_spin_lock+0x10c/0x110 kernel/locking/spinlock_debug.c:115
>  __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
>  _raw_spin_lock+0x5c/0x6c kernel/locking/spinlock.c:154
>  spin_lock include/linux/spinlock.h:349 [inline]
>  nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
>  nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
>  nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
>  nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
>  nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
>  evict+0xec/0x334 fs/inode.c:665
>  iput_final fs/inode.c:1748 [inline]
>  iput+0x2c4/0x324 fs/inode.c:1774
>  nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
>  generic_shutdown_super+0x8c/0x190 fs/super.c:491
>  kill_block_super+0x30/0x78 fs/super.c:1427
>  deactivate_locked_super+0x70/0xe8 fs/super.c:332
>  deactivate_super+0xd0/0xd4 fs/super.c:363
>  cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
>  __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
>  task_work_run+0xc4/0x14c kernel/task_work.c:177
>  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: 8b2c4ecc f85f818c 1200056b 8b2b52ab (f82b6988)
> ---[ end trace 0000000000000000 ]---
> ----------------
> Code disassembly (best guess):
>    0:   8b2c4ecc        add     x12, x22, w12, uxtw #3
>    4:   f85f818c        ldur    x12, [x12, #-8]
>    8:   1200056b        and     w11, w11, #0x3
>    c:   8b2b52ab        add     x11, x21, w11, uxtw #4
> * 10:   f82b6988        str     x8, [x12, x11] <-- trapping instruction
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches

This is the same UAF bug as below:

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

The bugfix for this is the patch titled "fs: fix UAF/GPF bug in
nilfs_mdt_destroy", which is already merged in the mainline.

I confirmed that the above patch suppresses the bug by using the C-reproducer.

Ryusuke Konishi