In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch Sy

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

nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch

Syzbot reported a kernel BUG triggered within nilfs_copy_dirty_pages(),
which copies dirty DAT file folios/pages to its shadow page cache. The
BUG occurs when a retrieved dirty folio/page unexpectedly loses its
'dirty' status.

This issue arises because, since the commit referenced below, the 'dirty'
flag of a folio/page can be cleared asynchronously after the filesystem
detects metadata corruption and transitions to read-only mode.

Resolve the issue by returning an -EROFS error if the filesystem has
transitioned to read-only mode. Also change the behavior to issue a
kernel warning only once instead of triggering a kernel BUG when this
unexpected 'dirty' state is detected while the filesystem is not in
read-only mode.