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CVE-2024-49883

Estado: ModificadaAlta (7.8)—

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

ext4: aovid use-after-free in ext4_ext_insert_extent()

As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is reallocated in ext4_ext_create_new_leaf(), we'll use the stale path and cause UAF. Below is a sample trace with dummy values:

So use *ppath to update the path to avoid the above problem.

Detalles técnicos trazas, registros y código del informe original
ext4_ext_insert_extent
  path = *ppath = 2000
  ext4_ext_create_new_leaf(ppath)
    ext4_find_extent(ppath)
      path = *ppath = 2000
      if (depth > path[0].p_maxdepth)
            kfree(path = 2000);
            *ppath = path = NULL;
      path = kcalloc() = 3000
      *ppath = 3000;
      return path;
  /* here path is still 2000, UAF! */
  eh = path[depth].p_hdr

==================================================================
BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330
Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179
CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866
Call Trace:
 <TASK>
 ext4_ext_insert_extent+0x26d4/0x3330
 ext4_ext_map_blocks+0xe22/0x2d40
 ext4_map_blocks+0x71e/0x1700
 ext4_do_writepages+0x1290/0x2800
[...]

Allocated by task 179:
 ext4_find_extent+0x81c/0x1f70
 ext4_ext_map_blocks+0x146/0x2d40
 ext4_map_blocks+0x71e/0x1700
 ext4_do_writepages+0x1290/0x2800
 ext4_writepages+0x26d/0x4e0
 do_writepages+0x175/0x700
[...]

Freed by task 179:
 kfree+0xcb/0x240
 ext4_find_extent+0x7c0/0x1f70
 ext4_ext_insert_extent+0xa26/0x3330
 ext4_ext_map_blocks+0xe22/0x2d40
 ext4_map_blocks+0x71e/0x1700
 ext4_do_writepages+0x1290/0x2800
 ext4_writepages+0x26d/0x4e0
 do_writepages+0x175/0x700
[...]
==================================================================

CVSS

Probabilidad de explotación (EPSS)

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.

CVE-2024-49883 es un use-after-free en el kernel Linux (AV:L, PR:L) explotable localmente para escalada de privilegios (T1068). La UAF en ext4_ext_insert_extent() permite corrupción de memoria que podría permitir ejecución de código (T1059) o negación de servicio (T1499.004, crash del kernel).

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

Execution PreventionThreat Intelligence ProgramRestrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationFilter Network Traffic

Tecnologías afectadas (2)

Debian — Debian LinuxLinux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: aovid use-after-free in ext4_ext_insert_extent()\n\nAs Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is\nreallocated in ext4_ext_create_new_leaf(), we'll use the stale path and\ncause UAF. Below is a sample trace with dummy values:\n\next4_ext_insert_extent\n  path = *ppath = 2000\n  ext4_ext_create_new_leaf(ppath)\n    ext4_find_extent(ppath)\n      path = *ppath = 2000\n      if (depth > path[0].p_maxdepth)\n            kfree(path = 2000);\n            *ppath = path = NULL;\n      path = kcalloc() = 3000\n      *ppath = 3000;\n      return path;\n  /* here path is still 2000, UAF! */\n  eh = path[depth].p_hdr\n\n==================================================================\nBUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330\nRead of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179\nCPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866\nCall Trace:\n <TASK>\n ext4_ext_insert_extent+0x26d4/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n[...]\n\nAllocated by task 179:\n ext4_find_extent+0x81c/0x1f70\n ext4_ext_map_blocks+0x146/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n\nFreed by task 179:\n kfree+0xcb/0x240\n ext4_find_extent+0x7c0/0x1f70\n ext4_ext_insert_extent+0xa26/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n==================================================================\n\nSo use *ppath to update the path to avoid the above problem."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: evitar use-after-free en ext4_ext_insert_extent() Como mencionó Ojaswin en Link, en ext4_ext_insert_extent(), si la ruta se reasigna en ext4_ext_create_new_leaf(), usaremos la ruta obsoleta y causaremos UAF. A continuación, se muestra un seguimiento de muestra con valores ficticios: ext4_ext_insert_extent path = *ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = *ppath = 2000 if (depth &gt; path[0].p_maxdepth) kfree(path = 2000); *ppath = path = NULL; path = kcalloc() = 3000 *ppath = 3000; return path; /* aquí la ruta sigue siendo 2000, UAF! */ eh = path[depth].p_hdr ===================================================================== ERROR: KASAN: slab-use-after-free en ext4_ext_insert_extent+0x26d4/0x3330 Lectura de tamaño 8 en la dirección ffff8881027bf7d0 por la tarea kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 No contaminado 6.11.0-rc2-dirty #866 Seguimiento de llamadas:  ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...] Asignado por la tarea 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] Liberado por la tarea 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...]==================================================================  Así que use *ppath para actualizar el path para evitar el problema de arriba"
    }
  ],
  "lastModified": "2026-08-04T11:20:55.747",
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