CVE-2025-38627

Estado: ModificadaAlta (7.8)—

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

f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic

The decompress_io_ctx may be released asynchronously after I/O completion. If this file is deleted immediately after read, and the kworker of processing post_read_wq has not been executed yet due to high workloads, It is possible that the inode(f2fs_inode_info) is evicted and freed before it is used f2fs_free_dic.

This patch store compress_algorithm and sbi in dic to avoid inode UAF.

In addition, the previous solution is deprecated in [1] may cause system hang. [1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org

Detalles técnicos trazas, registros y código del informe original

    The UAF case as below:
    Thread A                                      Thread B
    - f2fs_decompress_end_io
     - f2fs_put_dic
      - queue_work
        add free_dic work to post_read_wq
                                                   - do_unlink
                                                    - iput
                                                     - evict
                                                      - call_rcu
    This file is deleted after read.

    Thread C                                 kworker to process post_read_wq
    - rcu_do_batch
     - f2fs_free_inode
      - kmem_cache_free
     inode is freed by rcu
                                             - process_scheduled_works
                                              - f2fs_late_free_dic
                                               - f2fs_free_dic
                                                - f2fs_release_decomp_mem
                                      read (dic->inode)->i_compress_algorithm

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.17%
Percentil entre todas las CVEs puntuadas: 6
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %

UAF en kernel (CWE-416) con acceso local (AV:L, PR:L) sin interacción. Impacto: DoS por crash/cuelgue de sistema al liberar memoria durante procesamiento asincrónico en post_read_wq.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic\n\nThe decompress_io_ctx may be released asynchronously after\nI/O completion. If this file is deleted immediately after read,\nand the kworker of processing post_read_wq has not been executed yet\ndue to high workloads, It is possible that the inode(f2fs_inode_info)\nis evicted and freed before it is used f2fs_free_dic.\n\n    The UAF case as below:\n    Thread A                                      Thread B\n    - f2fs_decompress_end_io\n     - f2fs_put_dic\n      - queue_work\n        add free_dic work to post_read_wq\n                                                   - do_unlink\n                                                    - iput\n                                                     - evict\n                                                      - call_rcu\n    This file is deleted after read.\n\n    Thread C                                 kworker to process post_read_wq\n    - rcu_do_batch\n     - f2fs_free_inode\n      - kmem_cache_free\n     inode is freed by rcu\n                                             - process_scheduled_works\n                                              - f2fs_late_free_dic\n                                               - f2fs_free_dic\n                                                - f2fs_release_decomp_mem\n                                      read (dic->inode)->i_compress_algorithm\n\nThis patch store compress_algorithm and sbi in dic to avoid inode UAF.\n\nIn addition, the previous solution is deprecated in [1] may cause system hang.\n[1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: f2fs: compress: fix UAF de f2fs_inode_info en f2fs_free_dic El decompress_io_ctx puede liberarse de forma asíncrona tras la finalización de la E/S. Si este archivo se elimina inmediatamente después de la lectura, y el kworker del procesamiento de post_read_wq aún no se ha ejecutado debido a las altas cargas de trabajo, es posible que el inodo (f2fs_inode_info) se desaloje y se libere antes de que se use f2fs_free_dic. El caso de UAF como se muestra a continuación: Hilo A Hilo B - f2fs_decompress_end_io - f2fs_put_dic - queue_work añadir trabajo free_dic a post_read_wq - do_unlink - iput - evict - call_rcu Este archivo se elimina tras la lectura. Hilo C kworker para procesar post_read_wq - rcu_do_batch - f2fs_free_inode - kmem_cache_free inodo liberado por rcu - process_scheduled_works - f2fs_late_free_dic - f2fs_free_dic - f2fs_release_decomp_mem lectura (dic-&gt;inode)-&gt;i_compress_algorithm). Este parche almacena compress_algorithm y sbi en dic para evitar el UAF del inodo. Además, la solución anterior está obsoleta en [1] y puede causar un bloqueo del sistema. [1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org"
    }
  ],
  "lastModified": "2026-07-30T06:23:32.153",
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