CVE-2026-23467 (GCVE-0-2026-23467)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-04-03 15:15
VLAI?
Title
drm/i915/dmc: Fix an unlikely NULL pointer deference at probe
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/i915/dmc: Fix an unlikely NULL pointer deference at probe intel_dmc_update_dc6_allowed_count() oopses when DMC hasn't been initialized, and dmc is thus NULL. That would be the case when the call path is intel_power_domains_init_hw() -> {skl,bxt,icl}_display_core_init() -> gen9_set_dc_state() -> intel_dmc_update_dc6_allowed_count(), as intel_power_domains_init_hw() is called *before* intel_dmc_init(). However, gen9_set_dc_state() calls intel_dmc_update_dc6_allowed_count() conditionally, depending on the current and target DC states. At probe, the target is disabled, but if DC6 is enabled, the function is called, and an oops follows. Apparently it's quite unlikely that DC6 is enabled at probe, as we haven't seen this failure mode before. It is also strange to have DC6 enabled at boot, since that would require the DMC firmware (loaded by BIOS); the BIOS loading the DMC firmware and the driver stopping / reprogramming the firmware is a poorly specified sequence and as such unlikely an intentional BIOS behaviour. It's more likely that BIOS is leaving an unintentionally enabled DC6 HW state behind (without actually loading the required DMC firmware for this). The tracking of the DC6 allowed counter only works if starting / stopping the counter depends on the _SW_ DC6 state vs. the current _HW_ DC6 state (since stopping the counter requires the DC5 counter captured when the counter was started). Thus, using the HW DC6 state is incorrect and it also leads to the above oops. Fix both issues by using the SW DC6 state for the tracking. This is v2 of the fix originally sent by Jani, updated based on the first Link: discussion below. (cherry picked from commit 2344b93af8eb5da5d496b4e0529d35f0f559eaf0)
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 88c1f9a4d36de61f87cc52aac670020b13d1ccaa , < 0b35d11fbbcfd1079c8489282a341944228835e3 (git)
Affected: 88c1f9a4d36de61f87cc52aac670020b13d1ccaa , < 631317825d44283abfe7a8374f13a76ce2032bb8 (git)
Affected: 88c1f9a4d36de61f87cc52aac670020b13d1ccaa , < ac57eb3b7d2ad649025b5a0fa207315f755ac4f6 (git)
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    Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc5 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/i915/display/intel_display_power_well.c",
            "drivers/gpu/drm/i915/display/intel_dmc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0b35d11fbbcfd1079c8489282a341944228835e3",
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              "versionType": "git"
            },
            {
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "ac57eb3b7d2ad649025b5a0fa207315f755ac4f6",
              "status": "affected",
              "version": "88c1f9a4d36de61f87cc52aac670020b13d1ccaa",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/i915/display/intel_display_power_well.c",
            "drivers/gpu/drm/i915/display/intel_dmc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.10",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0-rc5",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/i915/dmc: Fix an unlikely NULL pointer deference at probe\n\nintel_dmc_update_dc6_allowed_count() oopses when DMC hasn\u0027t been\ninitialized, and dmc is thus NULL.\n\nThat would be the case when the call path is\nintel_power_domains_init_hw() -\u003e {skl,bxt,icl}_display_core_init() -\u003e\ngen9_set_dc_state() -\u003e intel_dmc_update_dc6_allowed_count(), as\nintel_power_domains_init_hw() is called *before* intel_dmc_init().\n\nHowever, gen9_set_dc_state() calls intel_dmc_update_dc6_allowed_count()\nconditionally, depending on the current and target DC states. At probe,\nthe target is disabled, but if DC6 is enabled, the function is called,\nand an oops follows. Apparently it\u0027s quite unlikely that DC6 is enabled\nat probe, as we haven\u0027t seen this failure mode before.\n\nIt is also strange to have DC6 enabled at boot, since that would require\nthe DMC firmware (loaded by BIOS); the BIOS loading the DMC firmware and\nthe driver stopping / reprogramming the firmware is a poorly specified\nsequence and as such unlikely an intentional BIOS behaviour. It\u0027s more\nlikely that BIOS is leaving an unintentionally enabled DC6 HW state\nbehind (without actually loading the required DMC firmware for this).\n\nThe tracking of the DC6 allowed counter only works if starting /\nstopping the counter depends on the _SW_ DC6 state vs. the current _HW_\nDC6 state (since stopping the counter requires the DC5 counter captured\nwhen the counter was started). Thus, using the HW DC6 state is incorrect\nand it also leads to the above oops. Fix both issues by using the SW DC6\nstate for the tracking.\n\nThis is v2 of the fix originally sent by Jani, updated based on the\nfirst Link: discussion below.\n\n(cherry picked from commit 2344b93af8eb5da5d496b4e0529d35f0f559eaf0)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-03T15:15:46.483Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0b35d11fbbcfd1079c8489282a341944228835e3"
        },
        {
          "url": "https://git.kernel.org/stable/c/631317825d44283abfe7a8374f13a76ce2032bb8"
        },
        {
          "url": "https://git.kernel.org/stable/c/ac57eb3b7d2ad649025b5a0fa207315f755ac4f6"
        }
      ],
      "title": "drm/i915/dmc: Fix an unlikely NULL pointer deference at probe",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23467",
    "datePublished": "2026-04-03T15:15:46.483Z",
    "dateReserved": "2026-01-13T15:37:46.021Z",
    "dateUpdated": "2026-04-03T15:15:46.483Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23467\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-03T16:16:34.177\",\"lastModified\":\"2026-04-07T13:20:55.200\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ndrm/i915/dmc: Fix an unlikely NULL pointer deference at probe\\n\\nintel_dmc_update_dc6_allowed_count() oopses when DMC hasn\u0027t been\\ninitialized, and dmc is thus NULL.\\n\\nThat would be the case when the call path is\\nintel_power_domains_init_hw() -\u003e {skl,bxt,icl}_display_core_init() -\u003e\\ngen9_set_dc_state() -\u003e intel_dmc_update_dc6_allowed_count(), as\\nintel_power_domains_init_hw() is called *before* intel_dmc_init().\\n\\nHowever, gen9_set_dc_state() calls intel_dmc_update_dc6_allowed_count()\\nconditionally, depending on the current and target DC states. At probe,\\nthe target is disabled, but if DC6 is enabled, the function is called,\\nand an oops follows. Apparently it\u0027s quite unlikely that DC6 is enabled\\nat probe, as we haven\u0027t seen this failure mode before.\\n\\nIt is also strange to have DC6 enabled at boot, since that would require\\nthe DMC firmware (loaded by BIOS); the BIOS loading the DMC firmware and\\nthe driver stopping / reprogramming the firmware is a poorly specified\\nsequence and as such unlikely an intentional BIOS behaviour. It\u0027s more\\nlikely that BIOS is leaving an unintentionally enabled DC6 HW state\\nbehind (without actually loading the required DMC firmware for this).\\n\\nThe tracking of the DC6 allowed counter only works if starting /\\nstopping the counter depends on the _SW_ DC6 state vs. the current _HW_\\nDC6 state (since stopping the counter requires the DC5 counter captured\\nwhen the counter was started). Thus, using the HW DC6 state is incorrect\\nand it also leads to the above oops. Fix both issues by using the SW DC6\\nstate for the tracking.\\n\\nThis is v2 of the fix originally sent by Jani, updated based on the\\nfirst Link: discussion below.\\n\\n(cherry picked from commit 2344b93af8eb5da5d496b4e0529d35f0f559eaf0)\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0b35d11fbbcfd1079c8489282a341944228835e3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/631317825d44283abfe7a8374f13a76ce2032bb8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ac57eb3b7d2ad649025b5a0fa207315f755ac4f6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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