{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-31488",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-31488"
  ],
  "published": "2026-04-22T13:57:42Z",
  "summary": "drm/amd/display: Do not skip unrelated mode changes in DSC validation",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amd/display: Do not skip unrelated mode changes in DSC validation\n\nStarting with commit 17ce8a6907f7 (\"drm/amd/display: Add dsc pre-validation in\natomic check\"), amdgpu resets the CRTC state mode_changed flag to false when\nrecomputing the DSC configuration results in no timing change for a particular\nstream.\n\nHowever, this is incorrect in scenarios where a change in MST/DSC configuration\nhappens in the same KMS commit as another (unrelated) mode change. For example,\nthe integrated panel of a laptop may be configured differently (e.g., HDR\nenabled/disabled) depending on whether external screens are attached. In this\ncase, plugging in external DP-MST screens may result in the mode_changed flag\nbeing dropped incorrectly for the integrated panel if its DSC configuration\ndid not change during precomputation in pre_validate_dsc().\n\nAt this point, however, dm_update_crtc_state() has already created new streams\nfor CRTCs with DSC-independent mode changes. In turn,\namdgpu_dm_commit_streams() will never release the old stream, resulting in a\nmemory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to\nthe new stream either, which manifests as a use-after-free when the stream gets\ndisabled later on:\n\nBUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu]\nWrite of size 4 at addr ffff88813d836524 by task kworker/9:9/29977\n\nWorkqueue: events drm_mode_rmfb_work_fn\nCall Trace:\n <TASK>\n dump_stack_lvl+0x6e/0xa0\n print_address_description.constprop.0+0x88/0x320\n ? dc_stream_release+0x25/0x90 [amdgpu]\n print_report+0xfc/0x1ff\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __virt_addr_valid+0x225/0x4e0\n ? dc_stream_release+0x25/0x90 [amdgpu]\n kasan_report+0xe1/0x180\n ? dc_stream_release+0x25/0x90 [amdgpu]\n kasan_check_range+0x125/0x200\n dc_stream_release+0x25/0x90 [amdgpu]\n dc_state_destruct+0x14d/0x5c0 [amdgpu]\n dc_state_release.part.0+0x4e/0x130 [amdgpu]\n dm_atomic_destroy_state+0x3f/0x70 [amdgpu]\n drm_atomic_state_default_clear+0x8ee/0xf30\n ? drm_mode_object_put.part.0+0xb1/0x130\n __drm_atomic_state_free+0x15c/0x2d0\n atomic_remove_fb+0x67e/0x980\n\nSince there is no reliable way of figuring out whether a CRTC has unrelated\nmode changes pending at the time of DSC validation, remember the value of the\nmode_changed flag from before the point where a CRTC was marked as potentially\naffected by a change in DSC configuration. Reset the mode_changed flag to this\nearlier value instead in pre_validate_dsc().\n\n(cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.175",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-31488"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/da1d0ed31e9802fd99384f43cc63678a5a11cb41"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/21159d8b335a6b9f44cbb506733013a902ae2da4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/10862e344b4d6434642a48c87d765813fc0b0ba7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8a5edc97fd9c6415ff2eff872748439a97e3c3d8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/111208b5b7ebcdadb3f922cc52d8425f0fa91b33"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/aed3d041ab061ec8a64f50a3edda0f4db7280025"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable path is reached through local DRM/KMS ioctls, especially DRM_IOCTL_MODE_ATOMIC on an amdgpu primary device, not through network input.\nAC:L - On an affected AMD display setup with DSC/MST-capable outputs, the bad state transition is deterministically triggered by a crafted atomic modeset combining MST/DSC changes with an unrelated mode change.\nPR:L - The attacker must be a local DRM client with access to the primary node and current DRM master capability; this is attainable by an unprivileged graphical-session user and does not require real root.\nUI:N - Once the attacker has the local DRM access, exploitation is driven by ioctls and later framebuffer/CRTC teardown without requiring a separate victim action.\nS:U - The corruption occurs within the kernel display driver and affects the same kernel security authority, with no VM escape or cross-scope boundary involved.\nC:H - The bug creates a use-after-free of a kernel dc_stream_state object, and kernel UAF memory corruption is defensibly capable of exposing arbitrary kernel memory.\nI:H - The observed failure is a write through kref_put to a freed object, and a reclaimable kernel UAF write can be shaped into memory corruption or control-flow compromise.\nA:H - The commit documents a KASAN use-after-free in dc_stream_release, and this class of kernel memory corruption can reliably crash or destabilize the system."
    }
  }
}