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CVE-2026-89445 (GCVE-0-2026-89445)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:29
VLAI
Title
iommufd: Fix UAF in selftest IOPF reporting
Summary
In the Linux kernel, the following vulnerability has been resolved: iommufd: Fix UAF in selftest IOPF reporting IOMMUFD selftest TRIGGER_IOPF borrows an attach handle from group->pasid_array without synchronizing against PASID detach, then a concurrent iommu_report_device_fault() can dereference that borrowed handle's domain pointer after the detach erases the handle and frees the backing struct iommufd_attach_handle. TRIGGER_IOPF then dereferences the freed handle, causing a UAF. Fix by adding a iopf_rwsem in mock_dev to follow the expected design of a real driver. Hold its read side across the whole iommu_report_device_fault() call, and its write side around every path that attaches, detaches, or replaces a device domain. This can block new reports and drains in-flight reports before an old attach handle or the IOPF fault parameter can be removed. Also take the write side while registering a mock device, since it can invoke the mock driver's default-domain attach callback.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ddee19971081b42615d62f4fdada21274708ed4d , < cab2895729516799384d48560e6fca105fb3f927 (git)
Affected: ddee19971081b42615d62f4fdada21274708ed4d , < e27e90bde68b2ab92e63ed19caad1ef57188bea0 (git)
Affected: ddee19971081b42615d62f4fdada21274708ed4d , < 8c07df7cdfcf52f1ff276c588612aabc6c6b8399 (git)
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Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/iommufd/selftest.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Fix UAF in selftest IOPF reporting\n\nIOMMUFD selftest TRIGGER_IOPF borrows an attach handle from\ngroup-\u003epasid_array without synchronizing against PASID detach,\nthen a concurrent iommu_report_device_fault() can dereference\nthat borrowed handle\u0027s domain pointer after the detach erases\nthe handle and frees the backing struct iommufd_attach_handle.\nTRIGGER_IOPF then dereferences the freed handle, causing a UAF.\n\nFix by adding a iopf_rwsem in mock_dev to follow the expected design\nof a real driver. Hold its read side across the whole\niommu_report_device_fault() call, and its write side around every\npath that attaches, detaches, or replaces a device domain.\nThis can block new reports and drains in-flight reports before an old\nattach handle or the IOPF fault parameter can be removed.\nAlso take the write side while registering a mock device, since\nit can invoke the mock driver\u0027s default-domain attach callback."
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              "value": "AV:L - The UAF is reached only via local ioctls on /dev/iommu (or VFIO-compat /dev/vfio/vfio): IOMMU_TEST_CMD TRIGGER_IOPF calls iommu_report_device_fault() while a concurrent PASID/RID detach frees the attach handle. No network or packet-receive path exists.\nAC:L - The attacker controls both sides of the race by issuing concurrent IOMMU_TEST_OP_TRIGGER_IOPF and PASID_DETACH/REPLACE or mock-domain destroy on the same fd; iommu_attach_handle_get() does not keep the handle alive after lookup, so no victim timing or uncontrollable layout is required.\nPR:L - iommufd_fops_open() and IOMMU_TEST_CMD perform no capability checks; /dev/iommu is 0660 and MOCK_DOMAIN creates an IOPF-capable mock device without physical assignment, so an unprivileged local user with iommufd access (selftest/syzkaller kernels or VFIO/iommufd group membership) can trigger it without init-namespace root.\nUI:N - Exploitation requires no victim action; the attacker programmatically opens iommufd, creates a mock domain, attaches a PASID, and races TRIGGER_IOPF against detach through their own file descriptors and ioctls.\nS:C - The freed object is struct iommufd_attach_handle used by iommu_report_device_fault() to dispatch domain-\u003eiopf_handler and complete IOMMU page faults; pre-fix TRIGGER_IOPF also accepted any bound idev, so corrupting those handles can hijack IOMMU fault/DMA isolation across the device-assignment boundary.\nC:H - Use-after-free of iommufd_attach_handle lets an attacker reclaim the slab and control the domain pointer later read as attach_handle-\u003edomain-\u003eiopf_handler, enabling arbitrary kernel reads through the IOPF handler and fault-queue path.\nI:H - The UAF is a function-pointer dereference of domain-\u003eiopf_handler plus later handle use in iommufd_fault_iopf_handler; heap spraying yields an arbitrary write and control-flow hijack in the IOMMU fault-completion path.\nA:H - Dereferencing the freed attach handle in find_fault_handler()/iommu_report_device_fault() causes a kernel oops or panic; the UAF is reliably crashable even when not fully exploited for code execution."
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    "datePublished": "2026-09-11T19:43:12.765Z",
    "dateReserved": "2026-09-11T19:38:34.704Z",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Fix UAF in selftest IOPF reporting\n\nIOMMUFD selftest TRIGGER_IOPF borrows an attach handle from\ngroup-\u003epasid_array without synchronizing against PASID detach,\nthen a concurrent iommu_report_device_fault() can dereference\nthat borrowed handle\u0027s domain pointer after the detach erases\nthe handle and frees the backing struct iommufd_attach_handle.\nTRIGGER_IOPF then dereferences the freed handle, causing a UAF.\n\nFix by adding a iopf_rwsem in mock_dev to follow the expected design\nof a real driver. Hold its read side across the whole\niommu_report_device_fault() call, and its write side around every\npath that attaches, detaches, or replaces a device domain.\nThis can block new reports and drains in-flight reports before an old\nattach handle or the IOPF fault parameter can be removed.\nAlso take the write side while registering a mock device, since\nit can invoke the mock driver\u0027s default-domain attach callback."
          }
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        "lastModified": "2026-09-13T07:17:09.093",
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      "current_release_date": "2026-09-17T18:52:01+00:00",
      "cve": "CVE-2026-89445",
      "id": "CVE-2026-89445",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: iommufd: Fix UAF in selftest IOPF reporting",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89445.json",
      "version": "3"
    },
    "suse_vex": {
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      "current_release_date": "2026-09-15T00:59:16Z",
      "cve": "CVE-2026-89445",
      "id": "CVE-2026-89445",
      "initial_release_date": "2026-09-12T16:28:21Z",
      "product_status:known_affected": "17",
      "product_status:known_not_affected": "336",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89445",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89445.json",
      "version": "4"
    }
  }
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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