CVE-2022-49287

Estado: ModificadaAlta (7)—

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

tpm: fix reference counting for struct tpm_chip

The following sequence of operations results in a refcount warning:

1. Open device /dev/tpmrm. 2. Remove module tpm_tis_spi. 3. Write a TPM command to the file descriptor opened at step 1.

The reason for this warning is the attempt to get the chip->dev reference in tpm_common_write() although the reference counter is already zero.

Since commit 8979b02aaf1d ("tpm: Fix reference count to main device") the extra reference used to prevent a premature zero counter is never taken, because the required TPM_CHIP_FLAG_TPM2 flag is never set.

Leer descripción completaMostrar menos

Fix this by moving the TPM 2 character device handling from tpm_chip_alloc() to tpm_add_char_device() which is called at a later point in time when the flag has been set in case of TPM2.

Commit fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") already introduced function tpm_devs_release() to release the extra reference but did not implement the required put on chip->devs that results in the call of this function.

Fix this by putting chip->devs in tpm_chip_unregister().

Finally move the new implementation for the TPM 2 handling into a new function to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the good case and error cases.

Detalles técnicos trazas, registros y código del informe original

------------[ cut here ]------------
WARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4
refcount_t: addition on 0; use-after-free.
Modules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac
sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4
brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes
raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm
snd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835]
CPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2
Hardware name: BCM2711
[<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14)
[<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8)
[<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108)
[<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8)
[<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4)
[<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm])
[<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm])
[<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0)
[<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc)
[<c05a7ee4>] (ksys_write) from [<c04001a0>] (ret_fast_syscall+0x0/0x4c)
Exception stack(0xc226bfa8 to 0xc226bff0)
bfa0:                   00000000 000105b4 00000003 beafe664 00000014 00000000
bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684
bfe0: 0000006c beafe648 0001056c b6eb6944
---[ end trace d4b8409def9b8b1f ]---

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.27%
Percentil entre todas las CVEs puntuadas: 18
Fecha de la puntuación: 6/10/2026

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 escalation75 %
Impacto principalT1059 Command and Scripting Interpreterexecution65 %

Vulnerabilidad local de use-after-free (CWE-416) con acceso local (AV:L) y privilegios bajos (PR:L) sin interacción requerida. Permite ejecución de código arbitrario tras escalada de privilegios al manipular referencias de kernel en TPM.

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 Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416

Referencias

JSON original (NVD)

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    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntpm: fix reference counting for struct tpm_chip\n\nThe following sequence of operations results in a refcount warning:\n\n1. Open device /dev/tpmrm.\n2. Remove module tpm_tis_spi.\n3. Write a TPM command to the file descriptor opened at step 1.\n\n------------[ cut here ]------------\nWARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4\nrefcount_t: addition on 0; use-after-free.\nModules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac\nsha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4\nbrcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes\nraspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm\nsnd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835]\nCPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2\nHardware name: BCM2711\n[<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14)\n[<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8)\n[<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108)\n[<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8)\n[<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4)\n[<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm])\n[<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm])\n[<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0)\n[<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc)\n[<c05a7ee4>] (ksys_write) from [<c04001a0>] (ret_fast_syscall+0x0/0x4c)\nException stack(0xc226bfa8 to 0xc226bff0)\nbfa0:                   00000000 000105b4 00000003 beafe664 00000014 00000000\nbfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684\nbfe0: 0000006c beafe648 0001056c b6eb6944\n---[ end trace d4b8409def9b8b1f ]---\n\nThe reason for this warning is the attempt to get the chip->dev reference\nin tpm_common_write() although the reference counter is already zero.\n\nSince commit 8979b02aaf1d (\"tpm: Fix reference count to main device\") the\nextra reference used to prevent a premature zero counter is never taken,\nbecause the required TPM_CHIP_FLAG_TPM2 flag is never set.\n\nFix this by moving the TPM 2 character device handling from\ntpm_chip_alloc() to tpm_add_char_device() which is called at a later point\nin time when the flag has been set in case of TPM2.\n\nCommit fdc915f7f719 (\"tpm: expose spaces via a device link /dev/tpmrm<n>\")\nalready introduced function tpm_devs_release() to release the extra\nreference but did not implement the required put on chip->devs that results\nin the call of this function.\n\nFix this by putting chip->devs in tpm_chip_unregister().\n\nFinally move the new implementation for the TPM 2 handling into a new\nfunction to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the\ngood case and error cases."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tpm: arreglo del recuento de referencias para struct tpm_chip La siguiente secuencia de operaciones genera una advertencia de recuento de referencias: 1. Abra el dispositivo /dev/tpmrm. 2. Elimine el módulo tpm_tis_spi. 3. Escriba un comando TPM en el descriptor de archivo abierto en el paso 1. ------------[ cortar aquí ]------------ ADVERTENCIA: CPU: 3 PID: 1161 en lib/refcount.c:25 kobject_get+0xa0/0xa4 refcount_t: adición en 0; use-after-free. Módulos vinculados en: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4 brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm snd_timer genet snd phy_generic soundcore [última descarga: spi_bcm2835] CPU: 3 PID: 1161 Comm: hold_open No contaminado 5.10.0ls-main-dirty #2 Nombre del hardware: BCM2711 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) desde [] (dump_stack+0xc4/0xd8) [] (dump_stack) from [] (__warn+0x104/0x108) [] (__warn) from [] (warn_slowpath_fmt+0x74/0xb8) [] (warn_slowpath_fmt) from [] (kobject_get+0xa0/0xa4) [] (kobject_get) desde [] (tpm_try_get_ops+0x14/0x54 [tpm]) [] (tpm_try_get_ops [tpm]) desde[] (tpm_common_write+0x38/0x60 [tpm]) [] (tpm_common_write [tpm]) desde[] (vfs_write+0xc4/0x3c0) [] (vfs_write) desde[] (ksys_write+0x58/0xcc) [] (ksys_write) desde[] (ret_fast_syscall+0x0/0x4c) Pila de excepciones (0xc226bfa8 a 0xc226bff0) bfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000 bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684 bfe0: 0000006c beafe648 0001056c b6eb6944 ---[ fin del seguimiento d4b8409def9b8b1f ]--- El motivo de esta advertencia es el intento de obtener el chip-&gt;dev referencia en tpm_common_write() aunque el contador de referencia ya es cero. Desde el commit 8979b02aaf1d (\"tpm: Fix reference count to main device\") la referencia adicional utilizada para evitar un contador cero prematuro nunca se toma, porque el indicador TPM_CHIP_FLAG_TPM2 requerido nunca se establece. Corrija esto moviendo la gestión del dispositivo de caracteres TPM 2 de tpm_chip_alloc() a tpm_add_char_device() que se llama en un punto posterior en el tiempo cuando el indicador se ha establecido en el caso de TPM2. el commit fdc915f7f719 (\"tpm: exponer espacios a través de un enlace de dispositivo /dev/tpmrm\") ya introdujo la función tpm_devs_release() para liberar la referencia adicional pero no implementó la función put en chip-&gt;devs requerida que da como resultado la llamada de esta función. Corrija esto colocando chip-&gt;devs en tpm_chip_unregister(). Finalmente, mueva la nueva implementación para la gestión de TPM 2 a una nueva función para evitar múltiples verificaciones del indicador TPM_CHIP_FLAG_TPM2 en los casos buenos y de error."
    }
  ],
  "lastModified": "2026-08-04T10:17:42.947",
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}