A: Root Cause Analysis: Looking at the given vulnerable code line and its context, the CWE-787 (Out-of-bounds Write) vulnerability exists in the code because the `i915_gem_alloc_object` function is called with the `size` parameter which is not validated. If the `size` parameter is too large, it can lead to an out-of-memory condition and cause the function to return an error. However, if the function does not handle this error properly, it can result in an out-of-bounds write vulnerability, which is CWE-787.