Kernel Vulnerability in Ceph Functionality of Linux by Vendor

CVE-2025-39879

What is CVE-2025-39879?

A vulnerability exists in the Linux kernel's Ceph functionality, specifically in the handling of folio_batch entries during memory management. The function ceph_process_folio_batch() incorrectly sets folio_batch entries to NULL, creating an illegal state that could lead to system crashes when ceph_writepages_start() is invoked. Recent changes to the code have made it possible for errors in this function to go unhandled, risking kernel NULL pointer dereferences and potential system instability. To mitigate this issue, it's advised to implement fixes by ensuring the ceph_shift_unused_folios_left() function is called immediately after ceph_process_folio_batch() to maintain the integrity of folio_batch entries.

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