CVE-2025-39878

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error<br /> <br /> The function move_dirty_folio_in_page_array() was created by commit<br /> ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") by<br /> moving code from ceph_writepages_start() to this function.<br /> <br /> This new function is supposed to return an error code which is checked<br /> by the caller (now ceph_process_folio_batch()), and on error, the<br /> caller invokes redirty_page_for_writepage() and then breaks from the<br /> loop.<br /> <br /> However, the refactoring commit has gone wrong, and it by accident, it<br /> always returns 0 (= success) because it first NULLs the pointer and<br /> then returns PTR_ERR(NULL) which is always 0. This means errors are<br /> silently ignored, leaving NULL entries in the page array, which may<br /> later crash the kernel.<br /> <br /> The simple solution is to call PTR_ERR() before clearing the pointer.