nilfs2: do not write dirty data after degenerating to read-only

Summary

In the Linux kernel, the following vulnerability has been resolved: nilfs2: do not write dirty data after degenerating to read-only According to syzbot's report, mark_buffer_dirty() called from nilfs_segctor_do_construct() outputs a warning with some patterns after nilfs2 detects metadata corruption and degrades to read-only mode. After such read-only degeneration, page cache data may be cleared through nilfs_clear_dirty_page() which may also clear the uptodate flag for their buffer heads. However, even after the degeneration, log writes are still performed by unmount processing etc., which causes mark_buffer_dirty() to be called for buffer heads without the "uptodate" flag and causes the warning. Since any writes should not be done to a read-only file system in the first place, this fixes the warning in mark_buffer_dirty() by letting nilfs_segctor_do_construct() abort early if in read-only mode. This also changes the retry check of nilfs_segctor_write_out() to avoid unnecessary log write retries if it detects -EROFS that nilfs_segctor_do_construct() returned.

Timeline

1. Sep 17, 2025, 2:56 PM UTCCVE published
2. Jan 14, 2026, 6:37 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. May 11, 2026, 7:42 PM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  3.10

References 9