FKIE_CVE-2026-31488

Vulnerability from fkie_nvd - Published: 2026-04-22 14:16 - Updated: 2026-04-27 15:16
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Do not skip unrelated mode changes in DSC validation Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in atomic check"), amdgpu resets the CRTC state mode_changed flag to false when recomputing the DSC configuration results in no timing change for a particular stream. However, this is incorrect in scenarios where a change in MST/DSC configuration happens in the same KMS commit as another (unrelated) mode change. For example, the integrated panel of a laptop may be configured differently (e.g., HDR enabled/disabled) depending on whether external screens are attached. In this case, plugging in external DP-MST screens may result in the mode_changed flag being dropped incorrectly for the integrated panel if its DSC configuration did not change during precomputation in pre_validate_dsc(). At this point, however, dm_update_crtc_state() has already created new streams for CRTCs with DSC-independent mode changes. In turn, amdgpu_dm_commit_streams() will never release the old stream, resulting in a memory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to the new stream either, which manifests as a use-after-free when the stream gets disabled later on: BUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu] Write of size 4 at addr ffff88813d836524 by task kworker/9:9/29977 Workqueue: events drm_mode_rmfb_work_fn Call Trace: <TASK> dump_stack_lvl+0x6e/0xa0 print_address_description.constprop.0+0x88/0x320 ? dc_stream_release+0x25/0x90 [amdgpu] print_report+0xfc/0x1ff ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x225/0x4e0 ? dc_stream_release+0x25/0x90 [amdgpu] kasan_report+0xe1/0x180 ? dc_stream_release+0x25/0x90 [amdgpu] kasan_check_range+0x125/0x200 dc_stream_release+0x25/0x90 [amdgpu] dc_state_destruct+0x14d/0x5c0 [amdgpu] dc_state_release.part.0+0x4e/0x130 [amdgpu] dm_atomic_destroy_state+0x3f/0x70 [amdgpu] drm_atomic_state_default_clear+0x8ee/0xf30 ? drm_mode_object_put.part.0+0xb1/0x130 __drm_atomic_state_free+0x15c/0x2d0 atomic_remove_fb+0x67e/0x980 Since there is no reliable way of figuring out whether a CRTC has unrelated mode changes pending at the time of DSC validation, remember the value of the mode_changed flag from before the point where a CRTC was marked as potentially affected by a change in DSC configuration. Reset the mode_changed flag to this earlier value instead in pre_validate_dsc(). (cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/10862e344b4d6434642a48c87d765813fc0b0ba7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/111208b5b7ebcdadb3f922cc52d8425f0fa91b33
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8a5edc97fd9c6415ff2eff872748439a97e3c3d8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aed3d041ab061ec8a64f50a3edda0f4db7280025
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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 \u003cTASK\u003e\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)"
    }
  ],
  "id": "CVE-2026-31488",
  "lastModified": "2026-04-27T15:16:09.223",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-22T14:16:46.453",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/10862e344b4d6434642a48c87d765813fc0b0ba7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/111208b5b7ebcdadb3f922cc52d8425f0fa91b33"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8a5edc97fd9c6415ff2eff872748439a97e3c3d8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/aed3d041ab061ec8a64f50a3edda0f4db7280025"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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