CVE-2026-43497 (GCVE-0-2026-43497)

Vulnerability from cvelistv5 – Published: 2026-05-21 12:12 – Updated: 2026-05-21 12:12
VLAI?
Title
fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free
Summary
In the Linux kernel, the following vulnerability has been resolved: fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free dlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages to userspace but sets no vm_ops on the VMA. This means the kernel cannot track active mmaps. When dlfb_realloc_framebuffer() replaces the backing buffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated. On USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages while userspace PTEs still reference them, resulting in a use-after-free: the process retains read/write access to freed kernel pages. Add vm_operations_struct with open/close callbacks that maintain an atomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(), check mmap_count and return -EBUSY if the buffer is currently mapped, preventing buffer replacement while userspace holds stale PTEs. Tested with PoC using dummy_hcd + raw_gadget USB device emulation.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 4f312c30f0368e8d2a76aa650dff73f23490b5e7 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 18dd358de72d57993422cbb5dfb29ccd74efe192 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < da9b065cedfd3b574f229d5be594e6aa47a27ae6 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a2c53a3822ee26e8d758071815b9ed3bf6669fc1 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 8de779dc40d35d39fa07387b6f921eb11df0f511 (git)
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Linux Linux Unaffected: 6.6.140 , ≤ 6.6.* (semver)
Unaffected: 6.12.88 , ≤ 6.12.* (semver)
Unaffected: 6.18.30 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc3 , ≤ * (original_commit_for_fix)
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{
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          "defaultStatus": "unaffected",
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          "programFiles": [
            "drivers/video/fbdev/udlfb.c",
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          "vendor": "Linux",
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              "status": "unaffected",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free\n\ndlfb_ops_mmap() uses remap_pfn_range() to map vmalloc framebuffer pages\nto userspace but sets no vm_ops on the VMA. This means the kernel cannot\ntrack active mmaps. When dlfb_realloc_framebuffer() replaces the backing\nbuffer via FBIOPUT_VSCREENINFO, existing mmap PTEs are not invalidated.\nOn USB disconnect, dlfb_ops_destroy() calls vfree() on the old pages\nwhile userspace PTEs still reference them, resulting in a use-after-free:\nthe process retains read/write access to freed kernel pages.\n\nAdd vm_operations_struct with open/close callbacks that maintain an\natomic mmap_count on struct dlfb_data. In dlfb_realloc_framebuffer(),\ncheck mmap_count and return -EBUSY if the buffer is currently mapped,\npreventing buffer replacement while userspace holds stale PTEs.\n\nTested with PoC using dummy_hcd + raw_gadget USB device emulation."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-21T12:12:47.150Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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        {
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        },
        {
          "url": "https://git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511"
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      ],
      "title": "fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43497",
    "datePublished": "2026-05-21T12:12:47.150Z",
    "dateReserved": "2026-05-01T14:12:56.013Z",
    "dateUpdated": "2026-05-21T12:12:47.150Z",
    "state": "PUBLISHED"
  },
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  }
}


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