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CVE-2026-64289

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: iommufd: Set upper bounds on cache invalidation entry_num and entry_len iommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len, each bounded only by U32_MAX. An entry_len beyond the kernel's struct size makes the copy helper verify the extra bytes are zero, scanning that excess in one uninterruptible pass; a multi-gigabyte value over zeroed user memory trips the soft-lockup watchdog. A large entry_num is the other half, driving the backend invalidation loop with no reschedule. The VT-d nested handler, for one, copies each entry and flushes caches per iteration, pinning the CPU on a non-preemptible kernel. Cap both in the ioctl. entry_len is held under PAGE_SIZE, above any request struct, and entry_num under 1 << 19, the order of a hardware invalidation queue and well beyond any real batch, bounding the per-call loop length.

Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-25 10:17:09.603000
Last modified
2026-11-06 17:18:45.487000
View original CVE JSON 
{
  "id": "CVE-2026-64289",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-07-25T10:17:09.603",
  "lastModified": "2026-11-06T17:18:45.487",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Set upper bounds on cache invalidation entry_num and entry_len\n\niommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len,\neach bounded only by U32_MAX. An entry_len beyond the kernel's struct size\nmakes the copy helper verify the extra bytes are zero, scanning that excess\nin one uninterruptible pass; a multi-gigabyte value over zeroed user memory\ntrips the soft-lockup watchdog.\n\nA large entry_num is the other half, driving the backend invalidation loop\nwith no reschedule. The VT-d nested handler, for one, copies each entry and\nflushes caches per iteration, pinning the CPU on a non-preemptible kernel.\n\nCap both in the ioctl. entry_len is held under PAGE_SIZE, above any request\nstruct, and entry_num under 1 << 19, the order of a hardware invalidation\nqueue and well beyond any real batch, bounding the per-call loop length."
    }
  ],
  "affected": [
    {
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      "affectedData": [
        {
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          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "drivers/iommu/iommufd/hw_pagetable.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
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              "versionType": "git",
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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              "versionType": "original_commit_for_fix",
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  ],
  "metrics": {
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          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
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        "exploitabilityScore": 1.8,
        "impactScore": 3.6
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    "ssvcV203": [
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          "role": "CISA Coordinator",
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  "weaknesses": [
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      "source": "[email protected]",
      "type": "Primary",
      "description": [
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  "configurations": [
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