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.
References
Configurations
Configuration 1 (hide)
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History
No history.
Information
Published : 2026-05-21 13:16
Updated : 2026-07-23 16:10
NVD link : CVE-2026-43497
Mitre link : CVE-2026-43497
CVE.ORG link : CVE-2026-43497
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free