In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix potential oob read in nilfsbtreecheck_delete()
The function nilfsbtreecheck_delete(), which checks whether degeneration to direct mapping occurs before deleting a b-tree entry, causes memory access outside the block buffer when retrieving the maximum key if the root node has no entries.
This does not usually happen because b-tree mappings with 0 child nodes are never created by mkfs.nilfs2 or nilfs2 itself. However, it can happen if the b-tree root node read from a device is configured that way, so fix this potential issue by adding a check for that case.