CVE-2022-49977
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead
ftrace_startup does not remove ops from ftrace_ops_list when ftrace_startup_enable fails:
If ops is dynamically allocated, it will be free later, in this case, is_ftrace_trampoline accesses NULL pointer:
Therefore, when ftrace_startup_enable fails, we need to rollback registration process and remove ops from ftrace_ops_list.
Detalles técnicos trazas, registros y código del informe original
register_ftrace_function
ftrace_startup
__register_ftrace_function
...
add_ftrace_ops(&ftrace_ops_list, ops)
...
...
ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1
...
return 0 // ops is in the ftrace_ops_list.
When ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything:
unregister_ftrace_function
ftrace_shutdown
if (unlikely(ftrace_disabled))
return -ENODEV; // return here, __unregister_ftrace_function is not executed,
// as a result, ops is still in the ftrace_ops_list
__unregister_ftrace_function
...
is_ftrace_trampoline
ftrace_ops_trampoline
do_for_each_ftrace_op(op, ftrace_ops_list) // OOPS! op may be NULL!
Syzkaller reports as follows:
[ 1203.506103] BUG: kernel NULL pointer dereference, address: 000000000000010b
[ 1203.508039] #PF: supervisor read access in kernel mode
[ 1203.508798] #PF: error_code(0x0000) - not-present page
[ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0
[ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI
[ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Tainted: G B W 5.10.0 #8
[ 1203.512324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0
[ 1203.514644] Code: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00
[ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246
[ 1203.520092] RAX: 0000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866
[ 1203.521469] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000000010b
[ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07
[ 1203.523550] R10: fffffbfff1be3160 R11: 0000000000000001 R12: 0000000000478399
[ 1203.524596] R13: 0000000000000000 R14: ffff888145088000 R15: 0000000000000008
[ 1203.525634] FS: 00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000
[ 1203.526801] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1203.527626] CR2: 000000000000010b CR3: 0000000170e1e001 CR4: 00000000003706e0
[ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.26%
- Percentil entre todas las CVEs puntuadas: 16
- 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).
Tecnologías afectadas (1)
CWE
- CWE-476
Referencias
- https://git.kernel.org/stable/c/4c34a2a6c9927c239dd2e295a03d49b37b618d2c
- https://git.kernel.org/stable/c/8569b4ada1e0b9bfaa125bd0c0967918b6560fa2
- https://git.kernel.org/stable/c/934e49f7d696afdae9f979abe3f308408184e17b
- https://git.kernel.org/stable/c/c3b0f72e805f0801f05fa2aa52011c4bfc694c44
- https://git.kernel.org/stable/c/d81bd6671f45fde4c3ac7fd7733c6e3082ae9d8e
- https://git.kernel.org/stable/c/dbd8c8fc60480e3faa3ae7e27ebe03371ecd1b77
- https://git.kernel.org/stable/c/ddffe882d74ef43a3494f0ab0c24baf076c45f96
- https://git.kernel.org/stable/c/e4ae97295984ff1b9b340ed18ae1b066f36b7835
JSON original (NVD)
Mostrar
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"description": [
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead\n\nftrace_startup does not remove ops from ftrace_ops_list when\nftrace_startup_enable fails:\n\nregister_ftrace_function\n ftrace_startup\n __register_ftrace_function\n ...\n add_ftrace_ops(&ftrace_ops_list, ops)\n ...\n ...\n ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1\n ...\n return 0 // ops is in the ftrace_ops_list.\n\nWhen ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything:\nunregister_ftrace_function\n ftrace_shutdown\n if (unlikely(ftrace_disabled))\n return -ENODEV; // return here, __unregister_ftrace_function is not executed,\n // as a result, ops is still in the ftrace_ops_list\n __unregister_ftrace_function\n ...\n\nIf ops is dynamically allocated, it will be free later, in this case,\nis_ftrace_trampoline accesses NULL pointer:\n\nis_ftrace_trampoline\n ftrace_ops_trampoline\n do_for_each_ftrace_op(op, ftrace_ops_list) // OOPS! op may be NULL!\n\nSyzkaller reports as follows:\n[ 1203.506103] BUG: kernel NULL pointer dereference, address: 000000000000010b\n[ 1203.508039] #PF: supervisor read access in kernel mode\n[ 1203.508798] #PF: error_code(0x0000) - not-present page\n[ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0\n[ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI\n[ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Tainted: G B W 5.10.0 #8\n[ 1203.512324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014\n[ 1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0\n[ 1203.514644] Code: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00\n[ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246\n[ 1203.520092] RAX: 0000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866\n[ 1203.521469] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000000010b\n[ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07\n[ 1203.523550] R10: fffffbfff1be3160 R11: 0000000000000001 R12: 0000000000478399\n[ 1203.524596] R13: 0000000000000000 R14: ffff888145088000 R15: 0000000000000008\n[ 1203.525634] FS: 00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000\n[ 1203.526801] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 1203.527626] CR2: 000000000000010b CR3: 0000000170e1e001 CR4: 00000000003706e0\n[ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n\nTherefore, when ftrace_startup_enable fails, we need to rollback registration\nprocess and remove ops from ftrace_ops_list."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ftrace: Se corrige la desreferencia del puntero NULL en is_ftrace_trampoline cuando ftrace está inactivo ftrace_startup no elimina las operaciones de ftrace_ops_list cuando ftrace_startup_enable falla: register_ftrace_function ftrace_startup __register_ftrace_function ... add_ftrace_ops(&ftrace_ops_list, ops) ... ... ftrace_startup_enable // si ftrace no se modificó, ftrace_disabled se establece en 1 ... return 0 // las operaciones están en ftrace_ops_list. Cuando ftrace_disabled = 1, unregister_ftrace_function simplemente regresa sin hacer nada: unregister_ftrace_function ftrace_shutdown if (unlikely(ftrace_disabled)) return -ENODEV; // regresa aquí, __unregister_ftrace_function no se ejecuta, // como resultado, ops todavía está en ftrace_ops_list __unregister_ftrace_function ... Si ops se asigna dinámicamente, estará libre más tarde, en este caso, is_ftrace_trampoline accede al puntero NULL: is_ftrace_trampoline ftrace_ops_trampoline do_for_each_ftrace_op(op, ftrace_ops_list) // ¡UPS! ¡op puede ser NULL! Syzkaller informa lo siguiente: [ 1203.506103] ERROR: desreferencia de puntero NULL del kernel, dirección: 000000000000010b [ 1203.508039] #PF: acceso de lectura del supervisor en modo kernel [ 1203.508798] #PF: error_code(0x0000) - página no presente [ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0 [ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI [ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Contaminado: GBW 5.10.0 #8 [1203.512324] Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 01/04/2014 [1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0 [1203.514644] Código: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00 [ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246 [ 1203.520092] RAX: 000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866 [ 1203.521469] RDX: 00000000000000000 RSI: 0000000000000008 RDI: 0000000000000010b [ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07 [ 1203.523550] R10: fffffbfff1be3160 R11: 000000000000001 R12: 0000000000478399 [ 1203.524596] R13: 000000000000000 R14: ffff888145088000 R15: 0000000000000008 [ 1203.525634] FS: 00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000 [ 1203.526801] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1203.527626] CR2: 00000000000010b CR3: 0000000170e1e001 CR4: 000000000003706e0 [ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Por lo tanto, cuando ftrace_startup_enable falla, debemos revertir el proceso de registro y eliminar las operaciones de ftrace_ops_list."
}
],
"lastModified": "2026-08-04T10:18:01.660",
"configurations": [
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