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CVE-2026-81016 (GCVE-0-2026-81016)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:29
VLAI
Title
platform/x86/amd/pmc: Propagate SMU errors and validate S2D address
Summary
In the Linux kernel, the following vulnerability has been resolved: platform/x86/amd/pmc: Propagate SMU errors and validate S2D address amd_stb_s2d_init() discards the return value of several S2D SMU commands. When the SMU refuses a command (e.g. "SMU cmd failed. err: 0xff") the failure is only noticed indirectly - if at all - and reported as -EIO, masking the real error. More seriously, the S2D_PHYS_ADDR_LOW/HIGH return values are ignored, so on failure phys_addr_low/hi are left uninitialised and the assembled address is passed straight to devm_ioremap(). When the SMU leaves them at zero this maps physical address 0 and trips the ioremap-on-RAM warning: amd_pmc AMDI000B:00: SMU cmd failed. err: 0xff ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff WARNING: CPU: 13 PID: 4592 at arch/x86/mm/ioremap.c:... Check the return value of each SMU command and propagate it, and reject a zero physical address before calling devm_ioremap().
Severity
7.7 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3d7d407dfb05b257e15cb0c6b056428a4a8c2e5d , < 8178f59d76570b152d836bde07f5997f15861f04 (git)
Affected: 3d7d407dfb05b257e15cb0c6b056428a4a8c2e5d , < 775d4cde1f9737796ce7d8393521e9e8c5b49891 (git)
Affected: 3d7d407dfb05b257e15cb0c6b056428a4a8c2e5d , < 0225c1d637687b03726f00ac65b6def843d2c464 (git)
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Linux Linux Affected: 5.18
Unaffected: 0 , < 5.18 (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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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/platform/x86/amd/pmc/mp1_stb.c"
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          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "version": "6.18.50",
              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
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                {
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                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
            }
          ]
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/pmc: Propagate SMU errors and validate S2D address\n\namd_stb_s2d_init() discards the return value of several S2D SMU commands.\nWhen the SMU refuses a command (e.g. \"SMU cmd failed. err: 0xff\") the\nfailure is only noticed indirectly - if at all - and reported as -EIO,\nmasking the real error.\n\nMore seriously, the S2D_PHYS_ADDR_LOW/HIGH return values are ignored, so\non failure phys_addr_low/hi are left uninitialised and the assembled\naddress is passed straight to devm_ioremap().  When the SMU leaves them at\nzero this maps physical address 0 and trips the ioremap-on-RAM warning:\n\n  amd_pmc AMDI000B:00: SMU cmd failed. err: 0xff\n  ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff\n  WARNING: CPU: 13 PID: 4592 at arch/x86/mm/ioremap.c:...\n\nCheck the return value of each SMU command and propagate it, and reject a\nzero physical address before calling devm_ioremap()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - amd_stb_s2d_init() runs from amd_pmc_probe() on the AMD PMC ACPI platform driver (AMDI0005\u2013AMDI000C and related IDs) during local device bind or module load; the SMU mailbox commands and devm_ioremap() are not reachable from network, Bluetooth, Wi-Fi, or USB packet paths.\nAC:L - On affected AMD platforms where SMU accepts S2D_TELEMETRY_SIZE but rejects S2D_PHYS_ADDR_LOW/HIGH (observed err 0xff), ignored failures leave phys_addr_low/hi uninitialized or zero and the subsequent ioremap is deterministic; stack zeroing makes address 0 reliable, with no race or attacker-uncontrollable layout.\nPR:N - The SMU queries and devm_ioremap() execute automatically in amd_pmc_probe() during ACPI/udev bind with no capable() check; enable_stb=1 is the vulnerable STB debug deployment (kernel cmdline or modprobe), after which kernel context runs the path without a user account or namespace privilege.\nUI:N - No victim interaction is required; the invalid ioremap occurs during automatic amd_pmc probe at boot or module load when STB is enabled, before any debugfs open, mount, or other user action.\nS:U - The bad physical-address ioremap, kernel warning, and any subsequent STB debugfs copy occur entirely inside the host kernel PMC driver; this is not a VM escape, IOMMU/DMA boundary bypass, or other cross-authority breakout.\nC:H - Ignored SMU failures pass uninitialized phys_addr_low/hi to devm_ioremap() for up to 16MB (S2D_TELEMETRY_DRAMBYTES_MAX); a non-RAM physical address creates a mapping that amd_stb_debugfs_open_v2 copies to userspace via memcpy_fromio on the 0644 stb_read node, yielding a large physical-memory disclosure.\nI:N - The driver only memcpy_fromio()s the STB mapping and never writes through stb_virt_addr; ioremap of RAM at address 0 is rejected, and there is no out-of-bounds write, use-after-free, or other kernel integrity or control-flow primitive.\nA:H - devm_ioremap() of physical address 0 hits WARN_ONCE in arch/x86/mm/ioremap.c, which panics under panic_on_warn; when the mapping fails, stb_virt_addr stays NULL while debugfs stb_read remains, so a later open does memcpy_fromio(NULL) and oopses the kernel."
            }
          ]
        }
      ],
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/0225c1d637687b03726f00ac65b6def843d2c464"
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    "cveId": "CVE-2026-81016",
    "datePublished": "2026-09-11T19:43:04.740Z",
    "dateReserved": "2026-08-26T14:34:25.813Z",
    "dateUpdated": "2026-09-13T06:29:18.491Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
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      "title": "platform/x86/amd/pmc: Propagate SMU errors and validate S2D address",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/pmc: Propagate SMU errors and validate S2D address\n\namd_stb_s2d_init() discards the return value of several S2D SMU commands.\nWhen the SMU refuses a command (e.g. \"SMU cmd failed. err: 0xff\") the\nfailure is only noticed indirectly - if at all - and reported as -EIO,\nmasking the real error.\n\nMore seriously, the S2D_PHYS_ADDR_LOW/HIGH return values are ignored, so\non failure phys_addr_low/hi are left uninitialised and the assembled\naddress is passed straight to devm_ioremap().  When the SMU leaves them at\nzero this maps physical address 0 and trips the ioremap-on-RAM warning:\n\n  amd_pmc AMDI000B:00: SMU cmd failed. err: 0xff\n  ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff\n  WARNING: CPU: 13 PID: 4592 at arch/x86/mm/ioremap.c:...\n\nCheck the return value of each SMU command and propagate it, and reject a\nzero physical address before calling devm_ioremap()."
          }
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        "lastModified": "2026-09-13T07:17:08.107",
        "metrics": {
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                "baseScore": 7.7,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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        "vulnStatus": "Received"
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      "cve": "CVE-2026-81016",
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      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "185",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: platform/x86/amd/pmc: Propagate SMU errors and validate S2D address",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-81016.json",
      "version": "3"
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      "cve": "CVE-2026-81016",
      "id": "CVE-2026-81016",
      "initial_release_date": "2026-09-15T01:03:57Z",
      "product_status:known_affected": "168",
      "product_status:known_not_affected": "185",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-81016",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-81016.json",
      "version": "2"
    }
  }
}



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