CVE-2025-23132

Summary

In the Linux kernel, the following vulnerability has been resolved:

f2fs: quota: fix to avoid warning in dquot_writeback_dquots()

F2FS-fs (dm-59): checkpoint=enable has some unwritten data.

————[ cut here ]———— WARNING: CPU: 6 PID: 8013 at fs/quota/dquot.c:691 dquot_writeback_dquots+0x2fc/0x308 pc : dquot_writeback_dquots+0x2fc/0x308 lr : f2fs_quota_sync+0xcc/0x1c4 Call trace: dquot_writeback_dquots+0x2fc/0x308 f2fs_quota_sync+0xcc/0x1c4 f2fs_write_checkpoint+0x3d4/0x9b0 f2fs_issue_checkpoint+0x1bc/0x2c0 f2fs_sync_fs+0x54/0x150 f2fs_do_sync_file+0x2f8/0x814 __f2fs_ioctl+0x1960/0x3244 f2fs_ioctl+0x54/0xe0 __arm64_sys_ioctl+0xa8/0xe4 invoke_syscall+0x58/0x114

checkpoint and f2fs_remount may race as below, resulting triggering warning in dquot_writeback_dquots().

atomic write remount - do_remount - down_write(&sb->s_umount); - f2fs_remount

• ioctl
• f2fs_do_sync_file
• f2fs_sync_fs
• f2fs_write_checkpoint - block_operations

  • locked = down_read_trylock(&sbi->sb->s_umount)

    fail to lock due to the write lock was held by remount - up_write(&sb->s_umount);

  • f2fs_quota_sync
  • dquot_writeback_dquots
  • WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount)) : trigger warning because s_umount lock was unlocked by remount

If checkpoint comes from mount/umount/remount/freeze/quotactl, caller of checkpoint has already held s_umount lock, calling dquot_writeback_dquots() in the context should be safe.

So let's record task to sbi->umount_lock_holder, so that checkpoint can know whether the lock has held in the context or not by checking current w/ it.

In addition, in order to not misrepresent caller of checkpoint, we should not allow to trigger async checkpoint for those callers: mount/umount/remount/ freeze/quotactl.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/d7acf0a6c87aa282c86a36dbaa2f92fda88c5884
• https://git.kernel.org/stable/c/eb85c2410d6f581e957cd03a644ff6ddbe592af9

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