Syzbot reported that in directory operations after nilfs2 detects filesystem corruption and degrades to read-only, __block_write_begin_int(), which is called to prepare block writes, may fail the BUG_ON check for accesses exceeding the folio/page size, triggering a kernel bug. This was found to be because the "checked" flag of a page/folio was not cleared when it was discarded by nilfs2's own routine, which causes the sanity check of directory entries to be skipped when the directory page/folio is reloaded. So, fix that. This was necessary when the use of nilfs2's own page discard routine was applied to more than just metadata files. Link: https://lkml.kernel.org/r/20241017193359.5051-1-konishi.ryusuke@xxxxxxxxx Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption") Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Reported-by: syzbot+d6ca2daf692c7a82f959@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=d6ca2daf692c7a82f959 Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 5436eb0424bd..10def4b55995 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -401,6 +401,7 @@ void nilfs_clear_folio_dirty(struct folio *folio) folio_clear_uptodate(folio); folio_clear_mappedtodisk(folio); + folio_clear_checked(folio); head = folio_buffers(folio); if (head) {
