CVE-2026-90042

/// Technical description

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

ceph: properly decrypt filenames in vmalloc() buffers

The fscrypt subsystem uses the scatterlist crypto API, inheriting its

requirement that any buffers are in the linear mapping region. However,

the messenger client uses kvmalloc() to create buffers for messages,

which will occasionally place those buffers in the vmalloc() region when

physical memory fragmentation doesn't permit a large enough kmalloc().

The various callers of ceph_fname_to_usr() directly pass (slices of) raw

messages from the MDS without considering that the messages may be in

vmalloc() buffers, resulting in oopses especially on non-x86 platforms

(see 'Closes:' for more details and a reproducer).

Make ceph_fname_to_usr() explicitly tolerant of vmalloc()-allocated

fname->ctext, fname->name, and/or oname->name buffers, using `tname`

(which, when non-null, must be a linear address; when null, is briefly

allocated as necessary) as a bounce buffer to a

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References