drm/bridge: lt8912b: Fix crash on bridge detach

{
  "id": "e4ecef839fc1f6c9b13f83e0011a5e27ec399d9b1e9af88e1122cc68fb221b22",
  "url": "https://osv.dev/vulnerability/CVE-2023-52856",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "drm/bridge: lt8912b: Fix crash on bridge detach",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: drm/bridge: lt8912b: Fix crash on bridge detach The lt8912b driver, in its bridge detach function, calls drm_connector_unregister() and drm_connector_cleanup(). drm_connector_unregister() should be called only for connectors explicitly registered with drm_connector_register(), which is not the case in lt8912b. The driver's drm_connector_funcs.destroy hook is set to drm_connector_cleanup(). Thus the driver should not call either drm_connector_unregister() nor drm_connector_cleanup() in its lt8912_bridge_detach(), as they cause a crash on bridge detach: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Mem abort info: ESR = 0x0000000096000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x06: level 2 translation fault Data abort info: ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000000858f3000 [0000000000000000] pgd=0800000085918003, p4d=0800000085918003, pud=0800000085431003, pmd=0000000000000000 Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP Modules linked in: tidss(-) display_connector lontium_lt8912b tc358768 panel_lvds panel_simple drm_dma_helper drm_kms_helper drm drm_panel_orientation_quirks CPU: 3 PID: 462 Comm: rmmod Tainted: G W 6.5.0-rc2+ #2 Hardware name: Toradex Verdin AM62 on Verdin Developme",
    "evidence": "osv:CVE-2023-52856",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.15.139",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.63",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.5.12",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.2",
            "evidence": "/affected/1/ranges"
          }
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        "affected_versions": []
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    "severity": "unknown",
    "structured": {
      "id": "CVE-2023-52856",
      "aliases": [
        "CVE-2023-52856"
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      "affected": [
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                  "fixed": "7bf0cb8f40280a85034990dfe42be8ca8f80f37a"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
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      ],
      "modified": "2026-10-28T02:30:37.009722216Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/42071feab712ba2a139b8928f7e0f8d3a6fc719e",
        "https://git.kernel.org/stable/c/44283993144a03af9df31934d6c32bbd42d1a347",
        "https://git.kernel.org/stable/c/7bf0cb8f40280a85034990dfe42be8ca8f80f37a",
        "https://git.kernel.org/stable/c/b65e3249f3ca96e3c736af889461d80d675feab6",
        "https://git.kernel.org/stable/c/fcd9895e365474709844eeb31cfe53d912c3596e",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/52xxx/CVE-2023-52856.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-52856",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/52xxx/CVE-2023-52856.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-52856",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 504096,
  "published_at": "2024-05-21T15:31:50.569+00:00"
}