int __glXDisp_DestroyContext(__GLXclientState *cl, GLbyte *pc)
{
    xGLXDestroyContextReq *req = (xGLXDestroyContextReq *) pc;
    __GLXcontext *glxc;
    int err;

    if (!validGlxContext(cl->client, req->context, DixDestroyAccess,
			 &glxc, &err))
	    return err;

    FreeResourceByType(req->context, __glXContextRes, FALSE);
    return Success;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.