CVE-2023-53795
Estado: AplazadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
iommufd: IOMMUFD_DESTROY should not increase the refcount
syzkaller found a race where IOMMUFD_DESTROY increments the refcount:
As part of the sequence to join the two existing primitives together.
Allowing the refcount the be elevated without holding the destroy_rwsem violates the assumption that all temporary refcount elevations are protected by destroy_rwsem. Racing IOMMUFD_DESTROY with iommufd_object_destroy_user() will cause spurious failures:
The solution is to not increment the refcount on the IOMMUFD_DESTROY path at all. Instead use the xa_lock to serialize everything. The refcount check == 1 and xa_erase can be done under a single critical region. This avoids the need for any refcount incrementing.
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It has the downside that if userspace races destroy with other operations it will get an EBUSY instead of waiting, but this is kind of racing is already dangerous.
Detalles técnicos trazas, registros y código del informe original
obj = iommufd_get_object(ucmd->ictx, cmd->id, IOMMUFD_OBJ_ANY);
if (IS_ERR(obj))
return PTR_ERR(obj);
iommufd_ref_to_users(obj);
/* See iommufd_ref_to_users() */
if (!iommufd_object_destroy_user(ucmd->ictx, obj))
WARNING: CPU: 0 PID: 3076 at drivers/iommu/iommufd/device.c:477 iommufd_access_destroy+0x18/0x20 drivers/iommu/iommufd/device.c:478
Modules linked in:
CPU: 0 PID: 3076 Comm: syz-executor.0 Not tainted 6.3.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
RIP: 0010:iommufd_access_destroy+0x18/0x20 drivers/iommu/iommufd/device.c:477
Code: e8 3d 4e 00 00 84 c0 74 01 c3 0f 0b c3 0f 1f 44 00 00 f3 0f 1e fa 48 89 fe 48 8b bf a8 00 00 00 e8 1d 4e 00 00 84 c0 74 01 c3 <0f> 0b c3 0f 1f 44 00 00 41 57 41 56 41 55 4c 8d ae d0 00 00 00 41
RSP: 0018:ffffc90003067e08 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888109ea0300 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000ffffffff
RBP: 0000000000000004 R08: 0000000000000000 R09: ffff88810bbb3500
R10: ffff88810bbb3e48 R11: 0000000000000000 R12: ffffc90003067e88
R13: ffffc90003067ea8 R14: ffff888101249800 R15: 00000000fffffffe
FS: 00007ff7254fe6c0(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555557262da8 CR3: 000000010a6fd000 CR4: 0000000000350ef0
Call Trace:
<TASK>
iommufd_test_create_access drivers/iommu/iommufd/selftest.c:596 [inline]
iommufd_test+0x71c/0xcf0 drivers/iommu/iommufd/selftest.c:813
iommufd_fops_ioctl+0x10f/0x1b0 drivers/iommu/iommufd/main.c:337
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x84/0xc0 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcdCVSS
- 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: 0.14%
- Percentil entre todas las CVEs puntuadas: 3
- 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.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1499.004Application or System Exploitationimpact75 %
Vulnerabilidad de escalada local en kernel Linux (AV:L, PR:L) sin interacción. El race condition en iommufd causa fallos de integridad y DoS (WARNING/panic). Impacto: negación de servicio.
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
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2023-53795",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2ff4bed7fee72ba1abfcff5f11ae8f8e570353f2",
"lessThan": "495b327435b0298e9b3b434f5834d459a93673ce",
"versionType": "git"
},
{
"status": "affected",
"version": "2ff4bed7fee72ba1abfcff5f11ae8f8e570353f2",
"lessThan": "99f98a7c0d6985d5507c8130a981972e4b7b3bdc",
"versionType": "git"
}
],
"programFiles": [
"drivers/iommu/iommufd/device.c",
"drivers/iommu/iommufd/iommufd_private.h",
"drivers/iommu/iommufd/main.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.4.8",
"versionType": "semver",
"lessThanOrEqual": "6.4.*"
},
{
"status": "unaffected",
"version": "6.5",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/iommu/iommufd/device.c",
"drivers/iommu/iommufd/iommufd_private.h",
"drivers/iommu/iommufd/main.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-12-09T01:16:51.080",
"references": [
{
"url": "https://git.kernel.org/stable/c/495b327435b0298e9b3b434f5834d459a93673ce",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/99f98a7c0d6985d5507c8130a981972e4b7b3bdc",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Deferred",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: IOMMUFD_DESTROY should not increase the refcount\n\nsyzkaller found a race where IOMMUFD_DESTROY increments the refcount:\n\n obj = iommufd_get_object(ucmd->ictx, cmd->id, IOMMUFD_OBJ_ANY);\n if (IS_ERR(obj))\n return PTR_ERR(obj);\n iommufd_ref_to_users(obj);\n /* See iommufd_ref_to_users() */\n if (!iommufd_object_destroy_user(ucmd->ictx, obj))\n\nAs part of the sequence to join the two existing primitives together.\n\nAllowing the refcount the be elevated without holding the destroy_rwsem\nviolates the assumption that all temporary refcount elevations are\nprotected by destroy_rwsem. Racing IOMMUFD_DESTROY with\niommufd_object_destroy_user() will cause spurious failures:\n\n WARNING: CPU: 0 PID: 3076 at drivers/iommu/iommufd/device.c:477 iommufd_access_destroy+0x18/0x20 drivers/iommu/iommufd/device.c:478\n Modules linked in:\n CPU: 0 PID: 3076 Comm: syz-executor.0 Not tainted 6.3.0-rc1-syzkaller #0\n Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023\n RIP: 0010:iommufd_access_destroy+0x18/0x20 drivers/iommu/iommufd/device.c:477\n Code: e8 3d 4e 00 00 84 c0 74 01 c3 0f 0b c3 0f 1f 44 00 00 f3 0f 1e fa 48 89 fe 48 8b bf a8 00 00 00 e8 1d 4e 00 00 84 c0 74 01 c3 <0f> 0b c3 0f 1f 44 00 00 41 57 41 56 41 55 4c 8d ae d0 00 00 00 41\n RSP: 0018:ffffc90003067e08 EFLAGS: 00010246\n RAX: 0000000000000000 RBX: ffff888109ea0300 RCX: 0000000000000000\n RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000ffffffff\n RBP: 0000000000000004 R08: 0000000000000000 R09: ffff88810bbb3500\n R10: ffff88810bbb3e48 R11: 0000000000000000 R12: ffffc90003067e88\n R13: ffffc90003067ea8 R14: ffff888101249800 R15: 00000000fffffffe\n FS: 00007ff7254fe6c0(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 0000555557262da8 CR3: 000000010a6fd000 CR4: 0000000000350ef0\n Call Trace:\n <TASK>\n iommufd_test_create_access drivers/iommu/iommufd/selftest.c:596 [inline]\n iommufd_test+0x71c/0xcf0 drivers/iommu/iommufd/selftest.c:813\n iommufd_fops_ioctl+0x10f/0x1b0 drivers/iommu/iommufd/main.c:337\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:870 [inline]\n __se_sys_ioctl fs/ioctl.c:856 [inline]\n __x64_sys_ioctl+0x84/0xc0 fs/ioctl.c:856\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x38/0x80 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThe solution is to not increment the refcount on the IOMMUFD_DESTROY path\nat all. Instead use the xa_lock to serialize everything. The refcount\ncheck == 1 and xa_erase can be done under a single critical region. This\navoids the need for any refcount incrementing.\n\nIt has the downside that if userspace races destroy with other operations\nit will get an EBUSY instead of waiting, but this is kind of racing is\nalready dangerous."
}
],
"lastModified": "2026-08-04T10:19:21.540",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}