Boundaries check for DoFinished.

-- added size and totalSz in the function parameters;
-- BUFFER_ERROR returned in case of message overflow (piece larger than the message size);
-- INCOMPLETE_DATA returned in case of buffer overflow (piece smaller than the expected size);
-- removed unnecessary variable idx;
-- fixed the sniffer to adapt to the changes.

cyassl/internal.h

@@ -820,7 +820,7 @@ CYASSL_LOCAL void InitSSL_Method(CYASSL_METHOD*, ProtocolVersion);
 
 /* for sniffer */
 CYASSL_LOCAL int DoFinished(CYASSL* ssl, const byte* input, word32* inOutIdx,
-                            int sniff);
+                            word32 size, word32 totalSz, int sniff);
 CYASSL_LOCAL int DoApplicationData(CYASSL* ssl, byte* input, word32* inOutIdx);
 
 

src/internal.c

@@ -3664,28 +3664,36 @@ static int DoHelloRequest(CYASSL* ssl, const byte* input, word32* inOutIdx)
 }
 
 
-int DoFinished(CYASSL* ssl, const byte* input, word32* inOutIdx, int sniff)
+int DoFinished(CYASSL* ssl, const byte* input, word32* inOutIdx, word32 size,
+                                                      word32 totalSz, int sniff)
 {
-    int    finishedSz = ssl->options.tls ? TLS_FINISHED_SZ : FINISHED_SZ;
+    if ((ssl->options.tls ? TLS_FINISHED_SZ : FINISHED_SZ) != size)
-    word32 idx = *inOutIdx;
+        return BUFFER_ERROR;
 
     #ifdef CYASSL_CALLBACKS
         if (ssl->hsInfoOn) AddPacketName("Finished", &ssl->handShakeInfo);
         if (ssl->toInfoOn) AddLateName("Finished", &ssl->timeoutInfo);
     #endif
+
     if (sniff == NO_SNIFF) {
-        if (XMEMCMP(input + idx, &ssl->verifyHashes, finishedSz) != 0) {
+        if (XMEMCMP(input + *inOutIdx, &ssl->verifyHashes, size) != 0) {
             CYASSL_MSG("Verify finished error on hashes");
             return VERIFY_FINISHED_ERROR;
         }
     }
-    idx += finishedSz;
+
-    idx += ssl->keys.padSz;
+    /* increment beyond input + size should be checked against totalSz */
+    if (*inOutIdx + size + ssl->keys.padSz > totalSz)
+        return INCOMPLETE_DATA;
+
+    /* force input exhaustion at ProcessReply consuming padSz */
+    *inOutIdx += size + ssl->keys.padSz;
 
     if (ssl->options.side == CYASSL_CLIENT_END) {
         ssl->options.serverState = SERVER_FINISHED_COMPLETE;
         if (!ssl->options.resuming) {
             ssl->options.handShakeState = HANDSHAKE_DONE;
+
 #ifdef CYASSL_DTLS
             if (ssl->options.dtls) {
                 /* Other side has received our Finished, go to next epoch */
@@ -3699,6 +3707,7 @@ int DoFinished(CYASSL* ssl, const byte* input, word32* inOutIdx, int sniff)
         ssl->options.clientState = CLIENT_FINISHED_COMPLETE;
         if (ssl->options.resuming) {
             ssl->options.handShakeState = HANDSHAKE_DONE;
+
 #ifdef CYASSL_DTLS
             if (ssl->options.dtls) {
                 /* Other side has received our Finished, go to next epoch */
@@ -3709,7 +3718,6 @@ int DoFinished(CYASSL* ssl, const byte* input, word32* inOutIdx, int sniff)
         }
     }
 
-    *inOutIdx = idx;
     return 0;
 }
 
@@ -3818,7 +3826,7 @@ static int DoHandShakeMsgType(CYASSL* ssl, byte* input, word32* inOutIdx,
 
     case finished:
         CYASSL_MSG("processing finished");
-        ret = DoFinished(ssl, input, inOutIdx, NO_SNIFF);
+        ret = DoFinished(ssl, input, inOutIdx, size, totalSz, NO_SNIFF);
         break;
 
 #ifndef NO_CYASSL_SERVER

src/sniffer.c

@@ -1444,7 +1444,7 @@ static int ProcessClientHello(const byte* input, int* sslBytes,
 
 
 /* Process Finished */
-static int ProcessFinished(const byte* input, int* sslBytes, 
+static int ProcessFinished(const byte* input, int size, int* sslBytes,
                            SnifferSession* session, char* error)
 {
     SSL*   ssl;
@@ -1455,7 +1455,9 @@ static int ProcessFinished(const byte* input, int* sslBytes,
         ssl = session->sslServer;
     else
         ssl = session->sslClient;
-    ret = DoFinished(ssl, input, &inOutIdx, SNIFF);
+
+    ret = DoFinished(ssl, input, &inOutIdx, (word32) size, (word32) *sslBytes,
+                                                                         SNIFF);
     *sslBytes -= (int)inOutIdx;
 
     if (ret < 0) {
@@ -1533,7 +1535,7 @@ static int DoHandShake(const byte* input, int* sslBytes,
             break;
         case finished:
             Trace(GOT_FINISHED_STR);
-            ret = ProcessFinished(input, sslBytes, session, error);
+            ret = ProcessFinished(input, size, sslBytes, session, error);
             break;
         case client_hello:
             Trace(GOT_CLIENT_HELLO_STR);