CVE-2021-45689: Use of Uninitialized Resource in gfx-auxil

The vulnerability stems from the read_spirv function's unsafe usage pattern where an uninitialized buffer is passed to a Read implementation. The code uses Vec::with_capacity followed by unsafe pointer manipulation to create a byte slice without initializing memory first. This directly matches the CWE-908 description of using uninitialized resources and aligns with the advisory's specific mention of gfx_auxil::read_spirv as the problematic function. The GitHub issue analysis confirms this pattern and its security implications.