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CVE-2026-53283

Status: AnalyzedMedium (5.5)—

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

iommu/amd: Bounds-check devid in __rlookup_amd_iommu()

iommu_device_register() walks every device on the PCI bus via bus_for_each_dev() and calls amd_iommu_probe_device() for each. The inlined check_device() path computes the device's sbdf, calls rlookup_amd_iommu() to find the owning IOMMU, and only afterwards verifies devid <= pci_seg->last_bdf. __rlookup_amd_iommu() indexes rlookup_table[devid] with no bounds check of its own, so for a PCI device whose BDF is not described by the IVRS, the lookup reads past the end of the allocation before the caller's bounds check can run.

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This was harmless before commit e874c666b15b ("iommu/amd: Change rlookup, irq_lookup, and alias to use kvalloc()"): the table was a zeroed page-order allocation, so the over-read returned NULL and the caller's NULL check skipped the device. After that commit the table is a tight kvcalloc() and the over-read returns adjacent slab contents, which check_device() then dereferences as a struct amd_iommu *, causing a boot-time GPF.

Seen on Google Compute Engine ct6e VMs, where the virtualized IVRS describes only the four TPU endpoints 00:04.0-07.0; the gVNIC at 00:08.0 (devid 0x40) indexes 56 bytes past the 456-byte allocation, into the adjacent kmalloc-512 slab object:

Guard the array access in __rlookup_amd_iommu(). With the fix applied on 6.18.22, the gVNIC at 00:08.0 is skipped cleanly and the VM boots.

Technical details traces, logs and code from the original report
  pci 0000:00:04.0: Adding to iommu group 0
  pci 0000:00:05.0: Adding to iommu group 1
  pci 0000:00:06.0: Adding to iommu group 2
  pci 0000:00:07.0: Adding to iommu group 3
  Oops: general protection fault, probably for non-canonical address 0x3a64695f78746382: 0000 [#1] SMP NOPTI
  CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.22 #1
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/06/2025
  RIP: 0010:amd_iommu_probe_device+0x54/0x3a0
  Call Trace:
   __iommu_probe_device+0x107/0x520
   probe_iommu_group+0x29/0x50
   bus_for_each_dev+0x7e/0xe0
   iommu_device_register+0xc9/0x240
   iommu_go_to_state+0x9c0/0x1c60
   amd_iommu_init+0x14/0x40
   pci_iommu_init+0x16/0x60
   do_one_initcall+0x47/0x2f0

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Linux — Linux Kernel

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-53283",
  "cveTags": [],
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        "source": "nvd@nist.gov",
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          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
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              "versionType": "semver"
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              "versionType": "semver",
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              "status": "unaffected",
              "version": "7.0.10",
              "versionType": "semver",
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          "programFiles": [
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  "published": "2026-06-26T20:17:20.253",
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  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Bounds-check devid in __rlookup_amd_iommu()\n\niommu_device_register() walks every device on the PCI bus via\nbus_for_each_dev() and calls amd_iommu_probe_device() for each. The\ninlined check_device() path computes the device's sbdf, calls\nrlookup_amd_iommu() to find the owning IOMMU, and only afterwards\nverifies devid <= pci_seg->last_bdf. __rlookup_amd_iommu() indexes\nrlookup_table[devid] with no bounds check of its own, so for a PCI\ndevice whose BDF is not described by the IVRS, the lookup reads past\nthe end of the allocation before the caller's bounds check can run.\n\nThis was harmless before commit e874c666b15b (\"iommu/amd: Change\nrlookup, irq_lookup, and alias to use kvalloc()\"): the table was a\nzeroed page-order allocation, so the over-read returned NULL and the\ncaller's NULL check skipped the device. After that commit the table is\na tight kvcalloc() and the over-read returns adjacent slab contents,\nwhich check_device() then dereferences as a struct amd_iommu *,\ncausing a boot-time GPF.\n\nSeen on Google Compute Engine ct6e VMs, where the virtualized IVRS\ndescribes only the four TPU endpoints 00:04.0-07.0; the gVNIC at\n00:08.0 (devid 0x40) indexes 56 bytes past the 456-byte allocation,\ninto the adjacent kmalloc-512 slab object:\n\n  pci 0000:00:04.0: Adding to iommu group 0\n  pci 0000:00:05.0: Adding to iommu group 1\n  pci 0000:00:06.0: Adding to iommu group 2\n  pci 0000:00:07.0: Adding to iommu group 3\n  Oops: general protection fault, probably for non-canonical address 0x3a64695f78746382: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.22 #1\n  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/06/2025\n  RIP: 0010:amd_iommu_probe_device+0x54/0x3a0\n  Call Trace:\n   __iommu_probe_device+0x107/0x520\n   probe_iommu_group+0x29/0x50\n   bus_for_each_dev+0x7e/0xe0\n   iommu_device_register+0xc9/0x240\n   iommu_go_to_state+0x9c0/0x1c60\n   amd_iommu_init+0x14/0x40\n   pci_iommu_init+0x16/0x60\n   do_one_initcall+0x47/0x2f0\n\nGuard the array access in __rlookup_amd_iommu(). With the fix applied\non 6.18.22, the gVNIC at 00:08.0 is skipped cleanly and the VM boots."
    }
  ],
  "lastModified": "2026-07-08T03:56:46.757",
  "configurations": [
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      "nodes": [
        {
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}