{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-43497", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-43497" ], "published": "2026-05-21T12:13:01Z", "summary": "fbdev: udlfb: add vm_ops to dlfb_ops_mmap to prevent use-after-free", "details": "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.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v6", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7l", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v8", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-2712", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v6", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7l", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v8", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-2712", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-v6", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-v7", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-v7l", "binary_version": "1:6.1.58-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi6-rpi-v8", "binary_version": "1:6.1.58-1+rpt2" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.175" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.175" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.175", "compiled_filter": false }, "1:6.1.54-1+rpt2": { "linux_commit": "2906f7abdc03d4a92b6b0e2e0c87ea2a9dffe8f7", "upstream_version": "6.1.54", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.175" }, "1:6.1.58-1+rpt2": { "linux_commit": "ccf1586ad0663fa91238ac56abf6340d6d740d18", "upstream_version": "6.1.58", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.175" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-43497" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/60f711cfd580f86fea8284146ac133804e728f9a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5931f5651ee32bd41b3323256b31fcc8e71336ed" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e3d9865dacd7435b8465848428210d0f0c673311" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4f312c30f0368e8d2a76aa650dff73f23490b5e7" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/18dd358de72d57993422cbb5dfb29ccd74efe192" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/da9b065cedfd3b574f229d5be594e6aa47a27ae6" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a2c53a3822ee26e8d758071815b9ed3bf6669fc1" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8de779dc40d35d39fa07387b6f921eb11df0f511" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T13:16:28Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.3, "cvss_v3_severity": "High", "scenario": "AV:L - The entire exploit is driven by local syscalls (open/mmap/FBIOPUT_VSCREENINFO/close) on the /dev/fbN character device; the attacker is a local software user, not a malicious USB device feeding crafted data, so the vector to the vulnerable component is local rather than physical.\nAC:L - The attacker reliably performs the mmap + realloc-via-ioctl + close sequence and can detect the disconnect before closing; the freed-page mapping is then deterministic with no race or uncontrolled memory-layout condition required to trigger the UAF.\nPR:L - Exploitation requires read/write access to the framebuffer device node, which is available to an ordinary logged-in/video-group user (or kiosk app user) but not to a fully unprivileged unauthenticated actor.\nUI:R - The freeing vfree only runs after a USB disconnect (unregister_framebuffer), so completing the exploit depends on a disconnect event (undock/unplug) performed by the user or environment rather than by the attacker's own code.\nS:U - The use-after-free corrupts kernel memory within the same security authority (the kernel); there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The process keeps a read mapping to freed pages that are recycled for arbitrary kernel allocations, allowing disclosure of arbitrary kernel memory.\nI:H - The same mapping retains write access to the freed pages once reused by other kernel objects, providing an arbitrary-write primitive suitable for privilege escalation or control-flow hijack.\nA:H - A use-after-free of freed kernel pages readily causes memory corruption and a kernel panic/oops." } } }