fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free
Summary
| CVE | CVE-2026-43497 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-21 13:16:19 UTC |
| Updated | 2026-05-21 13:16:19 UTC |
| Description | 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. |
Risk And Classification
EPSS: 0.000240000 probability, percentile 0.070660000 (date 2026-05-28)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 7433914efd584b22bb49d3e1eee001f5d0525ecd 4f312c30f0368e8d2a76aa650dff73f23490b5e7 git | Not specified |
| CNA | Linux | Linux | affected 7433914efd584b22bb49d3e1eee001f5d0525ecd 18dd358de72d57993422cbb5dfb29ccd74efe192 git | Not specified |
| CNA | Linux | Linux | affected 7433914efd584b22bb49d3e1eee001f5d0525ecd da9b065cedfd3b574f229d5be594e6aa47a27ae6 git | Not specified |
| CNA | Linux | Linux | affected 7433914efd584b22bb49d3e1eee001f5d0525ecd a2c53a3822ee26e8d758071815b9ed3bf6669fc1 git | Not specified |
| CNA | Linux | Linux | affected 7433914efd584b22bb49d3e1eee001f5d0525ecd 8de779dc40d35d39fa07387b6f921eb11df0f511 git | Not specified |
| CNA | Linux | Linux | affected 4.19 | Not specified |
| CNA | Linux | Linux | unaffected 4.19 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.140 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.88 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.30 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.7 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1-rc3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/da9b065cedfd3b574f229d5be594e6aa47a27ae6 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4f312c30f0368e8d2a76aa650dff73f23490b5e7 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/18dd358de72d57993422cbb5dfb29ccd74efe192 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/a2c53a3822ee26e8d758071815b9ed3bf6669fc1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.