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Possible DnsServer memory leak reported by coverity #2870

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merged 2 commits into from
Jul 24, 2024
Merged

Possible DnsServer memory leak reported by coverity #2870

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426c52a
Fix memory leak reported by coverity.
slav-at-attachix Jul 24, 2024
4f13d32
Review recommendations.
slav-at-attachix Jul 24, 2024
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1 change: 1 addition & 0 deletions Sming/Components/Network/src/Network/DnsServer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@ void DnsServer::onReceive(pbuf* buf, IpAddress remoteIP, uint16_t remotePort)

unsigned requestLen = pbuf_copy_partial(buf, buffer, buf->tot_len, 0);
if(requestLen != buf->tot_len) {
delete[] buffer;
return;
}
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I was chewing on whether this check is actually necessary since by inspection we pass buf->tot_len so the call is guaranteed to succeed. Hence this is really just shutting up the static analyser.

If we just remove lines 87-89 the code becomes much simpler.

We should also remove line 101 as I cannot see any use case for the user-provided callback here.

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Something like these lines below ?

void DnsServer::onReceive(pbuf* buf, IpAddress remoteIP, uint16_t remotePort)
{
	debug_d("DNS REQ from %s:%d", remoteIP.toString().c_str(), remotePort);

	// Allocated buffer with additional room for answer
	char* buffer = new char[buf->tot_len + MAX_ANSWER_LENGTH];
	if(buffer == nullptr) {
		return;
	}

	unsigned requestLen = pbuf_copy_partial(buf, buffer, buf->tot_len, 0);
	
	debug_hex(DBG, "< DNS", buffer, requestLen);

	auto responseLen = processQuestion(buffer, requestLen);
	if(responseLen != 0) {
		debug_hex(DBG, "> DNS", buffer, responseLen);
		sendTo(remoteIP, remotePort, buffer, responseLen);
	}

	delete[] buffer;
}

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Yes, that's much cleaner!


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