drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN

{
  "id": "1b332c9306f0f3565d25e246b5367fc9d07d9ef942e5dbfc10df7d1a5f34a60e",
  "url": "https://osv.dev/vulnerability/CVE-2026-99007",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: drm/fb-helper: defer setup when fbdev_probe() fails, not just on -EAGAIN __drm_fb_helper_initial_config_and_unlock() calls drm_client_modeset_probe() first, which already fills in each mode_set->mode/num_connectors for every connected output, and only afterwards calls drm_fb_helper_single_fb_probe() to create fb_helper->fb and wire it into those mode_sets via drm_setup_crtcs_fb(). If drm_fb_helper_single_fb_probe() fails with anything other than -EAGAIN (e.g. dev->driver->fbdev_probe() itself fails), the function bails out before drm_setup_crtcs_fb() runs and before setting fb_helper->deferred_setup. The client is left with mode_sets that have a mode and connectors but mode_set->fb == NULL, and nothing marks this fb_helper as needing a retry. __drm_fb_helper_restore_fbdev_mode_unlocked() only skips committing when fb_helper->deferred_setup is set, so a later .restore() call (drm_lastclose() on process exit, in this report) commits the stale mode_set through drm_client_modeset_commit() -> drm_client_modeset_commit_atomic() -> __drm_atomic_helper_set_config(), which hits WARN_ON(!set->fb). Mark fb_helper->deferred_setup on any drm_fb_helper_single_fb_probe() failure, not just -EAGAIN, so restore keeps skipping the commit until a later hotplug event successfully re-probes and re-populates mode_set->fb. The real error code is still returned to the caller unchanged.",
    "evidence": "osv:CVE-2026-99007",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
          },
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            "value": "5.15.224",
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            "value": "6.1.191",
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        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-99007",
      "aliases": [
        "CVE-2026-99007"
      ],
      "affected": [
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              "type": "ECOSYSTEM",
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                  "introduced": "4.14.0"
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-11-01T02:30:53.646614267Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3b303696f61461b3569019d7fcac6a646652b2b4",
        "https://git.kernel.org/stable/c/423c871a586cff8b29f48db00e3c45c21d0e8121",
        "https://git.kernel.org/stable/c/4a2006c675758f0c765b36fec6b49d17e89159cf",
        "https://git.kernel.org/stable/c/4e7b508c7c60dec7a86b7eb2a1b7e6d174afa457",
        "https://git.kernel.org/stable/c/755c94d178b7e972bb766199d34e4ba4f63a89eb",
        "https://git.kernel.org/stable/c/9124411cb91b129ff3ffb0d723ecba7a5bf893f9",
        "https://git.kernel.org/stable/c/d510ed273854177f0a3ed330145858b2fe667f81",
        "https://git.kernel.org/stable/c/e5f8f6e0f0a18c77c04b757d72319d897a0b4bc1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99007.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-99007",
        "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/2026/99xxx/CVE-2026-99007.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-99007",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 521939,
  "published_at": "2026-10-23T12:20:32.381+00:00"
}