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CVE-2025-39878

Full vulnerability record from the local CVENow database.

Description

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

Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-23 06:15:47.377000
Last modified
2026-10-21 13:18:16.043000
View original CVE JSON 
{
  "id": "CVE-2025-39878",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-09-23T06:15:47.377",
  "lastModified": "2026-10-21T13:18:16.043",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix crash after fscrypt_encrypt_pagecache_blocks() error\n\nThe function move_dirty_folio_in_page_array() was created by commit\nce80b76dd327 (\"ceph: introduce ceph_process_folio_batch() method\") by\nmoving code from ceph_writepages_start() to this function.\n\nThis new function is supposed to return an error code which is checked\nby the caller (now ceph_process_folio_batch()), and on error, the\ncaller invokes redirty_page_for_writepage() and then breaks from the\nloop.\n\nHowever, the refactoring commit has gone wrong, and it by accident, it\nalways returns 0 (= success) because it first NULLs the pointer and\nthen returns PTR_ERR(NULL) which is always 0.  This means errors are\nsilently ignored, leaving NULL entries in the page array, which may\nlater crash the kernel.\n\nThe simple solution is to call PTR_ERR() before clearing the pointer."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nceph: corregir un fallo después de un error en fscrypt_encrypt_pagecache_blocks()\n\nLa función move_dirty_folio_in_page_array() fue creada por el commit\nce80b76dd327 ('ceph: introducir el método ceph_process_folio_batch()')\nmoviendo código de ceph_writepages_start() a esta función.\n\nEsta nueva función se supone que debe devolver un código de error que es verificado\npor la función llamadora (ahora ceph_process_folio_batch()), y en caso de error,\nla función llamadora invoca redirty_page_for_writepage() y luego sale del\nbucle.\n\nSin embargo, el commit de refactorización ha salido mal, y por accidente,\nsiempre devuelve 0 (= éxito) porque primero anula el puntero y\nluego devuelve PTR_ERR(NULL) que siempre es 0. Esto significa que los errores son\nignorados silenciosamente, dejando entradas NULL en el array de páginas, lo que puede\nprovocar un fallo posterior del kernel.\n\nLa solución simple es llamar a PTR_ERR() antes de limpiar el puntero."
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}