CVE-2025-68251erofs: avoid infinite loops due to corrupted subpage compact indexes

Official description

In the Linux kernel, the following vulnerability has been resolved: erofs: avoid infinite loops due to corrupted subpage compact indexes Robert reported an infinite loop observed by two crafted images. The root cause is that `clusterofs` can be larger than `lclustersize` for !NONHEAD `lclusters` in corrupted subpage compact indexes, e.g.: blocksize = lclustersize = 512 lcn = 6 clusterofs = 515 Move the corresponding check for full compress indexes to `z_erofs_load_lcluster_from_disk()` to also cover subpage compact compress indexes. It also fixes the position of `m->type >= Z_EROFS_LCLUSTER_TYPE_MAX` check, since it should be placed right after `z_erofs_load_{compact,full}_lcluster()`.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/b18a82503a67a530d48f5a5b429e162749fe2c89
• https://git.kernel.org/stable/c/dbfac1b85d0753996ddfef636934d431b588dd1f
• https://git.kernel.org/stable/c/8675447a8794983f2b7e694b378112772c17635e
• https://git.kernel.org/stable/c/e13d315ae077bb7c3c6027cc292401bc0f4ec683