In the Linux kernel, the following vulnerability has been resolved:
ocfs2: reject FITRIM ranges shorter than a cluster
ocfs2_trim_mainbm() trims the global bitmap in cluster units, but its
too-short range validation only checks sb->s_blocksize.
On filesystems with a cluster size larger than the block size, a FITRIM
range that is at least one block but shorter than one cluster is accepted
and shifted down to len == 0. The later start + len – 1 and len -= …
arithmetic then underflows and can drive trimming past the requested
range.
Reject ranges shorter than s_clustersize instead. That preserves the
existing -EINVAL behavior for requests that cannot discard even one
allocation unit and keeps zero-cluster trims out of the group walk.
