dp_link_settings_write in drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c in the Linux kernel through 5.14.14 allows a heap-based buffer overflow by an attacker who can write a string to the AMD GPU display drivers debug filesystem. There are no checks on size within parse_write_buffer_into_params when it uses the size of copy_from_user to copy a userspace buffer into a 40-byte heap buffer.