CVE-2025-39784 (GCVE-0-2025-39784)

Vulnerability from cvelistv5 – Published: 2025-09-11 16:56 – Updated: 2026-05-11 21:36
VLAI
Title
PCI: Fix link speed calculation on retrain failure
Summary
In the Linux kernel, the following vulnerability has been resolved: PCI: Fix link speed calculation on retrain failure When pcie_failed_link_retrain() fails to retrain, it tries to revert to the previous link speed. However it calculates that speed from the Link Control 2 register without masking out non-speed bits first. PCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to PCI_SPEED_UNKNOWN (0xff), which in turn causes a WARN splat in pcie_set_target_speed(): pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s pci 0000:00:01.1: retraining failed WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000 pcie_failed_link_retrain pci_device_add pci_scan_single_device Mask out the non-speed bits in PCIE_LNKCTL2_TLS2SPEED() and PCIE_LNKCAP_SLS2SPEED() so they don't incorrectly return PCI_SPEED_UNKNOWN. [bhelgaas: commit log, add details from https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: de9a6c8d5dbfedb5eb3722c822da0490f6a59a45 , < 16557320f378262b5c605b15edebd3642406992a (git)
Affected: de9a6c8d5dbfedb5eb3722c822da0490f6a59a45 , < 9989e0ca7462c62f93dbc62f684448aa2efb9226 (git)
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Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.16.4 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: Fix link speed calculation on retrain failure\n\nWhen pcie_failed_link_retrain() fails to retrain, it tries to revert to the\nprevious link speed.  However it calculates that speed from the Link\nControl 2 register without masking out non-speed bits first.\n\nPCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to\nPCI_SPEED_UNKNOWN (0xff), which in turn causes a WARN splat in\npcie_set_target_speed():\n\n  pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port\n  pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s\n  pci 0000:00:01.1: retraining failed\n  WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed\n  RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000\n  pcie_failed_link_retrain\n  pci_device_add\n  pci_scan_single_device\n\nMask out the non-speed bits in PCIE_LNKCTL2_TLS2SPEED() and\nPCIE_LNKCAP_SLS2SPEED() so they don\u0027t incorrectly return PCI_SPEED_UNKNOWN.\n\n[bhelgaas: commit log, add details from https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]"
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      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:36:13.426Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "title": "PCI: Fix link speed calculation on retrain failure",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39784",
    "datePublished": "2025-09-11T16:56:34.097Z",
    "dateReserved": "2025-04-16T07:20:57.130Z",
    "dateUpdated": "2026-05-11T21:36:13.426Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-10-23",
      "epss": "0.0013",
      "percentile": "0.02405"
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            ],
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        "configurations": [
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: Fix link speed calculation on retrain failure\n\nWhen pcie_failed_link_retrain() fails to retrain, it tries to revert to the\nprevious link speed.  However it calculates that speed from the Link\nControl 2 register without masking out non-speed bits first.\n\nPCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to\nPCI_SPEED_UNKNOWN (0xff), which in turn causes a WARN splat in\npcie_set_target_speed():\n\n  pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port\n  pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s\n  pci 0000:00:01.1: retraining failed\n  WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed\n  RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000\n  pcie_failed_link_retrain\n  pci_device_add\n  pci_scan_single_device\n\nMask out the non-speed bits in PCIE_LNKCTL2_TLS2SPEED() and\nPCIE_LNKCAP_SLS2SPEED() so they don\u0027t incorrectly return PCI_SPEED_UNKNOWN.\n\n[bhelgaas: commit log, add details from https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]"
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nPCI: Correcci\u00f3n del c\u00e1lculo de la velocidad del enlace en caso de fallo de reentrenamiento\n\nCuando pcie_failed_link_retrain() falla al reentrenar, intenta revertir a la velocidad de enlace anterior. Sin embargo, calcula esa velocidad desde el registro Link Control 2 sin enmascarar primero los bits que no son de velocidad.\n\nPCIE_LNKCTL2_TLS2SPEED() convierte dichos valores incorrectos a PCI_SPEED_UNKNOWN (0xff), lo que a su vez provoca un WARN splat en pcie_set_target_speed():\n\n  pci 0000:00:01.1: [1022:14ed] tipo 01 clase 0x060400 Puerto ra\u00edz PCIe\n  pci 0000:00:01.1: dispositivo roto, reentrenando enlace descendente no funcional a 2.5GT/s\n  pci 0000:00:01.1: reentrenamiento fallido\n  WARNING: CPU: 1 PID: 1 en drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed\n  RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000\n  pcie_failed_link_retrain\n  pci_device_add\n  pci_scan_single_device\n\nEnmascarar los bits que no son de velocidad en PCIE_LNKCTL2_TLS2SPEED() y PCIE_LNKCAP_SLS2SPEED() para que no devuelvan incorrectamente PCI_SPEED_UNKNOWN.\n\n[bhelgaas: registro de commit, a\u00f1adir detalles de https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]"
          }
        ],
        "id": "CVE-2025-39784",
        "lastModified": "2026-10-19T21:10:00.160",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 5.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
                "version": "3.1"
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              "source": "nvd@nist.gov",
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        "published": "2025-09-11T17:15:44.493",
        "references": [
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            "tags": [
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Analyzed",
        "weaknesses": [
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                "value": "NVD-CWE-noinfo"
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            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
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    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-06-30T10:33:48+00:00",
      "cve": "CVE-2025-39784",
      "id": "CVE-2025-39784",
      "initial_release_date": "2025-09-11T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: PCI link speed calculation DoS",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39784.json",
      "version": "3"
    }
  }
}



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