Small hack to avoid runtime error when using ubsan

mbedtls_ssl_read cannot be called with a NULL buffer even if len is 0, as those are passed to memcpy and compilers doesn't like that. Always pass a single byte (still len 0 so nothing is actually copied)

Small hack to avoid runtime error when using ubsan
2b8b7383 · Fabio Alessandrelli · a056e8dc · 2b8b7383
Commit 2b8b7383 authored Feb 20, 2019 by Fabio Alessandrelli
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stream_peer_mbed_tls.cpp modules/mbedtls/stream_peer_mbed_tls.cpp +4 -1

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--- a/modules/mbedtls/stream_peer_mbed_tls.cpp
+++ b/modules/mbedtls/stream_peer_mbed_tls.cpp
@@ -270,7 +270,10 @@ void StreamPeerMbedTLS::poll() {
 		return;
 	}

-	int ret = mbedtls_ssl_read(&ssl, NULL, 0);
+	// We could pass NULL as second parameter, but some behaviour sanitizers doesn't seem to like that.
+	// Passing a 1 byte buffer to workaround it.
+	uint8_t byte;
+	int ret = mbedtls_ssl_read(&ssl, &byte, 0);

 	if (ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
 		// Nothing to read/write (non blocking IO)