Buffer Handling Issue in Ceph for Linux Kernel by The Linux Foundation

CVE-2026-90042

What is CVE-2026-90042?

A vulnerability has been identified in the Linux kernel involving Ceph's handling of filenames within vmalloc() buffers. The fscrypt subsystem's interaction with the scatterlist crypto API requires that specific buffers be allocated in linear mapping. However, the messenger client can occasionally allocate these buffers incorrectly, resulting in potential memory access errors. This issue could lead to inconsistent behavior and data corruption, particularly on non-x86 platforms. Recent patches have introduced safeguards to ensure that the ceph_fname_to_usr() function can appropriately handle these allocations, thus reducing the risk of crashes and enhancing overall stability. The implemented solution involves using a bounce buffer to manage the unsafe pointers, thereby enforcing better memory safety and data integrity in message processing.

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