Fuzz Fix

GetPublicDhKey() assumes the ssl session owns the DH public key parts, and
tries to free them. They belong to the CTX initially, so it shouldn't be
freeing them, necessarily.

1. Add a check for weOwnDh first, then free the buffers if needed.
2. If there is a problem reading the keys, free the new buffers before exiting.
3. Set weOwnDh once the buffers and values have been stored
   successfully.

src/internal.c

@@ -21133,22 +21133,25 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
     int             group = 0;
 #endif
 
-    ssl->buffers.weOwnDH = 1;
+    if (ssl->buffers.weOwnDH) {
-
         if (ssl->buffers.serverDH_P.buffer) {
-        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap, DYNAMIC_TYPE_PUBLIC_KEY);
+            XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                    DYNAMIC_TYPE_PUBLIC_KEY);
             ssl->buffers.serverDH_P.buffer = NULL;
         }
 
         if (ssl->buffers.serverDH_G.buffer) {
-        XFREE(ssl->buffers.serverDH_G.buffer, ssl->heap, DYNAMIC_TYPE_PUBLIC_KEY);
+            XFREE(ssl->buffers.serverDH_G.buffer, ssl->heap,
+                    DYNAMIC_TYPE_PUBLIC_KEY);
             ssl->buffers.serverDH_G.buffer = NULL;
         }
 
         if (ssl->buffers.serverDH_Pub.buffer) {
-        XFREE(ssl->buffers.serverDH_Pub.buffer, ssl->heap, DYNAMIC_TYPE_PUBLIC_KEY);
+            XFREE(ssl->buffers.serverDH_Pub.buffer, ssl->heap,
+                    DYNAMIC_TYPE_PUBLIC_KEY);
             ssl->buffers.serverDH_Pub.buffer = NULL;
         }
+    }
 
     /* p */
     if ((args->idx - args->begin) + OPAQUE16_LEN > size) {
@@ -21190,6 +21193,9 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
 
     /* g */
     if ((args->idx - args->begin) + OPAQUE16_LEN > size) {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
         ERROR_OUT(BUFFER_ERROR, exit_gdpk);
     }
 
@@ -21197,6 +21203,9 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
     args->idx += OPAQUE16_LEN;
 
     if ((args->idx - args->begin) + length > size) {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
         ERROR_OUT(BUFFER_ERROR, exit_gdpk);
     }
 
@@ -21206,6 +21215,9 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
         ssl->buffers.serverDH_G.length = length;
     }
     else {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
         ERROR_OUT(MEMORY_ERROR, exit_gdpk);
     }
 
@@ -21215,6 +21227,12 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
 
     /* pub */
     if ((args->idx - args->begin) + OPAQUE16_LEN > size) {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
+        XFREE(ssl->buffers.serverDH_G.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_G.buffer = NULL;
         ERROR_OUT(BUFFER_ERROR, exit_gdpk);
     }
 
@@ -21222,6 +21240,12 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
     args->idx += OPAQUE16_LEN;
 
     if ((args->idx - args->begin) + length > size) {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
+        XFREE(ssl->buffers.serverDH_G.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_G.buffer = NULL;
         ERROR_OUT(BUFFER_ERROR, exit_gdpk);
     }
 
@@ -21231,11 +21255,18 @@ static int GetDhPublicKey(WOLFSSL* ssl, const byte* input, word32 size,
         ssl->buffers.serverDH_Pub.length = length;
     }
     else {
+        XFREE(ssl->buffers.serverDH_P.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_P.buffer = NULL;
+        XFREE(ssl->buffers.serverDH_G.buffer, ssl->heap,
+                DYNAMIC_TYPE_PUBLIC_KEY);
+        ssl->buffers.serverDH_G.buffer = NULL;
         ERROR_OUT(MEMORY_ERROR, exit_gdpk);
     }
 
     XMEMCPY(ssl->buffers.serverDH_Pub.buffer, input + args->idx,
                                                         length);
+    ssl->buffers.weOwnDH = 1;
     args->idx += length;
 
 #ifdef HAVE_FFDHE