The cmark_markdown_to_html function call uses free to release crashes

QString DeepSeekWidgetUI::convertMarkdownToHtml(const QString& markdown)
{
QByteArray byteArray = markdown.toUtf8();
const char* markdownCString = byteArray.constData();

char* html = cmark_markdown_to_html(markdownCString, strlen(markdownCString), CMARK_OPT_DEFAULT);
if (html == NULL)
{
	return markdown;
}

QString htmlText = QString::fromUtf8(html);

free(html);

return htmlText;

}

After calling the cmark_markdown_to_html function, I copied the data to the QString, then released the memory and crashed directly. I thought it was a problem with the QString::fromUtf8() function, so I tested it and executed free() before QString::fromUtf8(), and it crashed as well.

This is the result of the call after QString::fromUtf8()

This is the result of the call before QString::fromUtf8()

Start at the cmark_markdown_to_html API and inspect how the returned buffer is allocated and documented; reproduce the crash with the shown Qt caller. Determine the correct ownership and release behavior, then verify that conversion and cleanup no longer crash.