dnsserv.c asserts when no supported questions are requested
The patch for #10268 (moved) has a simple crasher that is easily exploited from the network if DNSPort is open to a LAN (e.g., if you are transparent proxying).
As [ticket:10268 #comment:11 andrea] hinted at, the added "if (!q) q = req->questions[i];" to the for loop ensures that "q" is always set to the first question, even if it's unsupported. In which case, the "if (!q)" check for NOTIMPL is dead code. Ultimately, you will eventually hit the "tor_assert" that was added to the "else" branch. Additionally, the "switch" block switches on "req->questions[i]->type", but the assignment to "supported_q" is "q" (which is always the first question) instead of "req->questions[i]", so it doesn't actually pick the first supported question -- it always picks the first question.