syzbot

EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
ext4 filesystem being mounted at /2182/bus supports timestamps until 2038-01-19 (0x7fffffff)
EXT4-fs error (device loop2): ext4_xattr_block_get:600: inode #15: comm syz.2.8852: corrupted xattr block 33: bad e_name length
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.8852/26509 is trying to acquire lock:
ffff888075f29068 (&dquot->dq_lock){+.+.}-{3:3}, at: wait_on_dquot fs/quota/dquot.c:358 [inline]
ffff888075f29068 (&dquot->dq_lock){+.+.}-{3:3}, at: dqget+0x6fc/0xeb0 fs/quota/dquot.c:985

but task is already holding lock:
ffff88807139a8c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_setattr+0x86b/0x1c90 fs/ext4/inode.c:5490

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&ei->xattr_sem){++++}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ext4_setattr+0x86b/0x1c90 fs/ext4/inode.c:5490
       notify_change+0xb0d/0xe10 fs/attr.c:499
       chown_common+0x3f9/0x5a0 fs/open.c:783
       do_fchownat+0x168/0x270 fs/open.c:814
       __do_sys_chown fs/open.c:834 [inline]
       __se_sys_chown fs/open.c:832 [inline]
       __x64_sys_chown+0x82/0x90 fs/open.c:832
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #4 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0x1e9d/0x20c0 fs/jbd2/transaction.c:448
       jbd2__journal_start+0x2bb/0x5b0 fs/jbd2/transaction.c:505
       jbd2_journal_start+0x2a/0x40 fs/jbd2/transaction.c:544
       ocfs2_start_trans+0x376/0x6c0 fs/ocfs2/journal.c:374
       ocfs2_shutdown_local_alloc+0x201/0xa10 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e2/0x890 fs/ocfs2/super.c:1881
       generic_shutdown_super+0x134/0x2b0 fs/super.c:693
       kill_block_super+0x44/0x90 fs/super.c:1660
       deactivate_locked_super+0x97/0x100 fs/super.c:481
       cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
       task_work_run+0x1ce/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #3 (&journal->j_trans_barrier){.+.+}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ocfs2_start_trans+0x36a/0x6c0 fs/ocfs2/journal.c:372
       ocfs2_shutdown_local_alloc+0x201/0xa10 fs/ocfs2/localalloc.c:416
       ocfs2_dismount_volume+0x1e2/0x890 fs/ocfs2/super.c:1881
       generic_shutdown_super+0x134/0x2b0 fs/super.c:693
       kill_block_super+0x44/0x90 fs/super.c:1660
       deactivate_locked_super+0x97/0x100 fs/super.c:481
       cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
       task_work_run+0x1ce/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (sb_internal#4){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_intwrite include/linux/fs.h:1755 [inline]
       ocfs2_start_trans+0x26b/0x6c0 fs/ocfs2/journal.c:370
       ocfs2_acquire_dquot+0x67b/0xaf0 fs/ocfs2/quota_global.c:848
       dqget+0x77c/0xeb0 fs/quota/dquot.c:990
       dquot_set_dqblk+0x2b/0xf90 fs/quota/dquot.c:2833
       quota_setquota+0x4b0/0x530 fs/quota/quota.c:310
       __do_sys_quotactl fs/quota/quota.c:961 [inline]
       __se_sys_quotactl+0x27b/0x950 fs/quota/quota.c:917
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&ocfs2_quota_ip_alloc_sem_key){++++}-{3:3}:
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       ocfs2_create_local_dquot+0x1a4/0x1790 fs/ocfs2/quota_local.c:1224
       ocfs2_acquire_dquot+0x7cf/0xaf0 fs/ocfs2/quota_global.c:871
       dqget+0x77c/0xeb0 fs/quota/dquot.c:990
       dquot_set_dqblk+0x2b/0xf90 fs/quota/dquot.c:2833
       quota_setquota+0x4b0/0x530 fs/quota/quota.c:310
       __do_sys_quotactl fs/quota/quota.c:961 [inline]
       __se_sys_quotactl+0x27b/0x950 fs/quota/quota.c:917
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&dquot->dq_lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       wait_on_dquot fs/quota/dquot.c:358 [inline]
       dqget+0x6fc/0xeb0 fs/quota/dquot.c:985
       dquot_transfer+0x2f9/0x6d0 fs/quota/dquot.c:2151
       ext4_setattr+0x87d/0x1c90 fs/ext4/inode.c:5491
       notify_change+0xb0d/0xe10 fs/attr.c:499
       chown_common+0x3f9/0x5a0 fs/open.c:783
       do_fchownat+0x168/0x270 fs/open.c:814
       __do_sys_lchown fs/open.c:839 [inline]
       __se_sys_lchown fs/open.c:837 [inline]
       __x64_sys_lchown+0x85/0x90 fs/open.c:837
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &dquot->dq_lock --> jbd2_handle --> &ei->xattr_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&ei->xattr_sem);
                               lock(jbd2_handle);
                               lock(&ei->xattr_sem);
  lock(&dquot->dq_lock);

 *** DEADLOCK ***

3 locks held by syz.2.8852/26509:
 #0: ffff88807b7e0418 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
 #1: ffff88807139ac10 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88807139ac10 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: chown_common+0x313/0x5a0 fs/open.c:773
 #2: ffff88807139a8c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_setattr+0x86b/0x1c90 fs/ext4/inode.c:5490

stack backtrace:
CPU: 0 PID: 26509 Comm: syz.2.8852 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 wait_on_dquot fs/quota/dquot.c:358 [inline]
 dqget+0x6fc/0xeb0 fs/quota/dquot.c:985
 dquot_transfer+0x2f9/0x6d0 fs/quota/dquot.c:2151
 ext4_setattr+0x87d/0x1c90 fs/ext4/inode.c:5491
 notify_change+0xb0d/0xe10 fs/attr.c:499
 chown_common+0x3f9/0x5a0 fs/open.c:783
 do_fchownat+0x168/0x270 fs/open.c:814
 __do_sys_lchown fs/open.c:839 [inline]
 __se_sys_lchown fs/open.c:837 [inline]
 __x64_sys_lchown+0x85/0x90 fs/open.c:837
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff64238f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff6432b5038 EFLAGS: 00000246 ORIG_RAX: 000000000000005e
RAX: ffffffffffffffda RBX: 00007ff6425e5fa0 RCX: 00007ff64238f6c9
RDX: ffffffffffffffff RSI: 000000000000ee01 RDI: 0000200000000080
RBP: 00007ff642411f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff6425e6038 R14: 00007ff6425e5fa0 R15: 00007ffe70801698
 </TASK>
EXT4-fs error (device loop2): ext4_get_inode_usage:905: inode #15: comm syz.2.8852: corrupted xattr block 33: bad e_name length