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CVE-2025-38346

Estado: ModificadaAlta (7.8)—

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

ftrace: Fix UAF when lookup kallsym after ftrace disabled

The following issue happens with a buggy module:

The problem is when a module triggers an issue with ftrace and sets ftrace_disable. The ftrace_disable is set when an anomaly is discovered and to prevent any more damage, ftrace stops all text modification. The issue that happened was that the ftrace_disable stops more than just the text modification.

When a module is loaded, its init functions can also be traced. Because kallsyms deletes the init functions after a module has loaded, ftrace saves them when the module is loaded and function tracing is enabled. This allows the output of the function trace to show the init function names instead of just their raw memory addresses.

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When a module is removed, ftrace_release_mod() is called, and if ftrace_disable is set, it just returns without doing anything more. The problem here is that it leaves the mod_list still around and if kallsyms is called, it will call into this code and access the module memory that has already been freed as it will return:

Where the "mod" no longer exists and triggers a UAF bug.

Detalles técnicos trazas, registros y código del informe original
BUG: unable to handle page fault for address: ffffffffc05d0218
PGD 1bd66f067 P4D 1bd66f067 PUD 1bd671067 PMD 101808067 PTE 0
Oops: Oops: 0000 [#1] SMP KASAN PTI
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
RIP: 0010:sized_strscpy+0x81/0x2f0
RSP: 0018:ffff88812d76fa08 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffffc0601010 RCX: dffffc0000000000
RDX: 0000000000000038 RSI: dffffc0000000000 RDI: ffff88812608da2d
RBP: 8080808080808080 R08: ffff88812608da2d R09: ffff88812608da68
R10: ffff88812608d82d R11: ffff88812608d810 R12: 0000000000000038
R13: ffff88812608da2d R14: ffffffffc05d0218 R15: fefefefefefefeff
FS:  00007fef552de740(0000) GS:ffff8884251c7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffc05d0218 CR3: 00000001146f0000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ftrace_mod_get_kallsym+0x1ac/0x590
 update_iter_mod+0x239/0x5b0
 s_next+0x5b/0xa0
 seq_read_iter+0x8c9/0x1070
 seq_read+0x249/0x3b0
 proc_reg_read+0x1b0/0x280
 vfs_read+0x17f/0x920
 ksys_read+0xf3/0x1c0
 do_syscall_64+0x5f/0x2e0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The above issue may happen as follows:
(1) Add kprobe tracepoint;
(2) insmod test.ko;
(3)  Module triggers ftrace disabled;
(4) rmmod test.ko;
(5) cat /proc/kallsyms; --> Will trigger UAF as test.ko already removed;
ftrace_mod_get_kallsym()
...
strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
...

  strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);

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.

UAF en kernel Linux (CWE-416) con acceso local (AV:L) y privilegios de usuario (PR:L). El atacante puede desencadenar ftrace_disable y lectura de /proc/kallsyms para corrupción de memoria o código.

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 InstallationBehavior Prevention on Endpoint

Tecnologías afectadas (2)

Debian — Debian LinuxLinux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nftrace: Fix UAF when lookup kallsym after ftrace disabled\n\nThe following issue happens with a buggy module:\n\nBUG: unable to handle page fault for address: ffffffffc05d0218\nPGD 1bd66f067 P4D 1bd66f067 PUD 1bd671067 PMD 101808067 PTE 0\nOops: Oops: 0000 [#1] SMP KASAN PTI\nTainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\nRIP: 0010:sized_strscpy+0x81/0x2f0\nRSP: 0018:ffff88812d76fa08 EFLAGS: 00010246\nRAX: 0000000000000000 RBX: ffffffffc0601010 RCX: dffffc0000000000\nRDX: 0000000000000038 RSI: dffffc0000000000 RDI: ffff88812608da2d\nRBP: 8080808080808080 R08: ffff88812608da2d R09: ffff88812608da68\nR10: ffff88812608d82d R11: ffff88812608d810 R12: 0000000000000038\nR13: ffff88812608da2d R14: ffffffffc05d0218 R15: fefefefefefefeff\nFS:  00007fef552de740(0000) GS:ffff8884251c7000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: ffffffffc05d0218 CR3: 00000001146f0000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n ftrace_mod_get_kallsym+0x1ac/0x590\n update_iter_mod+0x239/0x5b0\n s_next+0x5b/0xa0\n seq_read_iter+0x8c9/0x1070\n seq_read+0x249/0x3b0\n proc_reg_read+0x1b0/0x280\n vfs_read+0x17f/0x920\n ksys_read+0xf3/0x1c0\n do_syscall_64+0x5f/0x2e0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe above issue may happen as follows:\n(1) Add kprobe tracepoint;\n(2) insmod test.ko;\n(3)  Module triggers ftrace disabled;\n(4) rmmod test.ko;\n(5) cat /proc/kallsyms; --> Will trigger UAF as test.ko already removed;\nftrace_mod_get_kallsym()\n...\nstrscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);\n...\n\nThe problem is when a module triggers an issue with ftrace and\nsets ftrace_disable. The ftrace_disable is set when an anomaly is\ndiscovered and to prevent any more damage, ftrace stops all text\nmodification. The issue that happened was that the ftrace_disable stops\nmore than just the text modification.\n\nWhen a module is loaded, its init functions can also be traced. Because\nkallsyms deletes the init functions after a module has loaded, ftrace\nsaves them when the module is loaded and function tracing is enabled. This\nallows the output of the function trace to show the init function names\ninstead of just their raw memory addresses.\n\nWhen a module is removed, ftrace_release_mod() is called, and if\nftrace_disable is set, it just returns without doing anything more. The\nproblem here is that it leaves the mod_list still around and if kallsyms\nis called, it will call into this code and access the module memory that\nhas already been freed as it will return:\n\n  strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);\n\nWhere the \"mod\" no longer exists and triggers a UAF bug."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ftrace: Reparar UAF cuando se busca kallsym después de ftrace deshabilitado El siguiente problema ocurre con un módulo con errores: ERROR: no se puede controlar el error de página para la dirección: ffffffffc05d0218 PGD 1bd66f067 P4D 1bd66f067 PUD 1bd671067 PMD 101808067 PTE 0 Oops: Oops: 0000 [#1] SMP KASAN PTI Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS RIP: 0010:sized_strscpy+0x81/0x2f0 RSP: 0018:ffff88812d76fa08 EFLAGS: 00010246 RAX: 0000000000000000 RBX: fffffffc0601010 RCX: dffffc0000000000 RDX: 0000000000000038 RSI: dffffc0000000000 RDI: ffff88812608da2d RBP: 8080808080808080 R08: ffff88812608da2d R09: ffff88812608da68 R10: ffff88812608d82d R11: ffff88812608d810 R12: 000000000000038 R13: ffff88812608da2d R14: ffffffffc05d0218 R15: fefefefefefefeff FS: 00007fef552de740(0000) GS:ffff8884251c7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc05d0218 CR3: 00000001146f0000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 00000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Rastreo de llamadas:  ftrace_mod_get_kallsym+0x1ac/0x590 update_iter_mod+0x239/0x5b0 s_next+0x5b/0xa0 seq_read_iter+0x8c9/0x1070 seq_read+0x249/0x3b0 proc_reg_read+0x1b0/0x280 vfs_read+0x17f/0x920 ksys_read+0xf3/0x1c0 do_syscall_64+0x5f/0x2e0 entry_SYSCALL_64_after_hwframe+0x76/0x7e El problema anterior puede ocurrir de la siguiente manera: (1) Agregar punto de seguimiento de kprobe; (2) insmod test.ko; (3) El módulo activa ftrace deshabilitado; (4) rmmod test.ko; (5) cat /proc/kallsyms; --&gt; Activará UAF como test.ko ya eliminado; ftrace_mod_get_kallsym() ... strscpy(module_name, mod_map-&gt;mod-&gt;name, MODULE_NAME_LEN); ... El problema es cuando un módulo activa un problema con ftrace y establece ftrace_disable. ftrace_disable se establece cuando se descubre una anomalía y para evitar más daños, ftrace detiene toda modificación de texto. El problema que ocurrió fue que ftrace_disable detiene más que solo la modificación de texto. Cuando se carga un módulo, también se pueden rastrear sus funciones de inicio. Dado que kallsyms elimina las funciones de inicio después de cargar un módulo, ftrace las guarda cuando el módulo se carga y se habilita el seguimiento de funciones. Esto permite que la salida del seguimiento de funciones muestre los nombres de las funciones de inicio en lugar de solo sus direcciones de memoria. Al eliminar un módulo, se llama a ftrace_release_mod() y, si ftrace_disable está configurado, simplemente regresa sin hacer nada más. El problema es que deja la lista de mods (mod_list) aún activa, y si se llama a kallsyms, este ejecutará este código y accederá a la memoria del módulo ya liberada, ya que devolverá: strscpy(module_name, mod_map-&gt;mod-&gt;name, MODULE_NAME_LEN); Donde el \"mod\" ya no existe, lo que genera un error de UAF."
    }
  ],
  "lastModified": "2026-07-30T06:23:08.293",
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