Fix multiple reported issues.

src/internal.c

@@ -12053,17 +12053,27 @@ static int wolfSSLReceive(WOLFSSL* ssl, byte* buf, word32 sz)
 }
 
 
-/* Switch dynamic output buffer back to static, buffer is assumed clear */
+/* Switch dynamic output buffer back to static, discarding any pending output.
+ * Safe to call whether or not the buffer is dynamic; callers need not check
+ * dynamicFlag first. */
 void ShrinkOutputBuffer(WOLFSSL* ssl)
 {
     WOLFSSL_MSG("Shrinking output buffer");
-    XFREE(ssl->buffers.outputBuffer.buffer - ssl->buffers.outputBuffer.offset,
-          ssl->heap, DYNAMIC_TYPE_OUT_BUFFER);
+    if (ssl->buffers.outputBuffer.dynamicFlag) {
+        /* Discarded records may hold plaintext, so wipe before releasing,
+         * as ShrinkInputBuffer does. */
+        ForceZero(ssl->buffers.outputBuffer.buffer,
+                  ssl->buffers.outputBuffer.bufferSize);
+        XFREE(ssl->buffers.outputBuffer.buffer -
+                  ssl->buffers.outputBuffer.offset,
+              ssl->heap, DYNAMIC_TYPE_OUT_BUFFER);
+    }
     ssl->buffers.outputBuffer.buffer = ssl->buffers.outputBuffer.staticBuffer;
     ssl->buffers.outputBuffer.bufferSize  = STATIC_BUFFER_LEN;
     ssl->buffers.outputBuffer.dynamicFlag = 0;
     ssl->buffers.outputBuffer.offset      = 0;
-    /* idx and length are assumed to be 0. */
+    ssl->buffers.outputBuffer.idx         = 0;
+    ssl->buffers.outputBuffer.length      = 0;
 }
 
 

src/ssl.c

@@ -5705,6 +5705,15 @@ size_t wolfSSL_get_client_random(const WOLFSSL* ssl, unsigned char* out,
         ssl->earlyData = no_early_data;
         ssl->earlyDataSz = 0;
     #endif
+    #ifdef HAVE_RPK
+        /* Drop the negotiated cert types so one peer's choice cannot carry into
+         * the next handshake. Clearing the counts is enough: every read of the
+         * type arrays is gated on its count. */
+        ssl->options.rpkState.sending_ClientCertTypeCnt = 0;
+        ssl->options.rpkState.sending_ServerCertTypeCnt = 0;
+        ssl->options.rpkState.received_ClientCertTypeCnt = 0;
+        ssl->options.rpkState.received_ServerCertTypeCnt = 0;
+    #endif
 
     #if defined(HAVE_TLS_EXTENSIONS) && !defined(NO_TLS)
         TLSX_FreeAll(ssl->extensions, ssl->heap);

src/tls.c

@@ -13540,6 +13540,22 @@ static int TLSX_ClientCertificateType_Parse(WOLFSSL* ssl, const byte* input,
     else if (msgType == server_hello || msgType == encrypted_extensions) {
         /* parse it in client side */
         if (length == 1) {
+            /* Same offered-vs-received binding as server_cert_type: an
+             * unsolicited value lets the peer pick the form this client
+             * presents its own credential in. */
+            if (ssl->options.rpkState.sending_ClientCertTypeCnt == 0) {
+                WOLFSSL_MSG("client_cert_type received but never offered");
+                WOLFSSL_ERROR_VERBOSE(UNSUPPORTED_EXTENSION);
+                return UNSUPPORTED_EXTENSION;
+            }
+            if (!IsCertTypeListed(*input,
+                    ssl->options.rpkState.sending_ClientCertTypeCnt,
+                    ssl->options.rpkState.sending_ClientCertTypes)) {
+                WOLFSSL_MSG("client_cert_type value was not offered");
+                WOLFSSL_ERROR_VERBOSE(UNSUPPORTED_EXTENSION);
+                return UNSUPPORTED_EXTENSION;
+            }
+
             ssl->options.rpkState.received_ClientCertTypeCnt  = 1;
             ssl->options.rpkState.received_ClientCertTypes[0] = *input;
         }
@@ -13740,6 +13756,23 @@ static int TLSX_ServerCertificateType_Parse(WOLFSSL* ssl, const byte* input,
         if (length != 1)                     /* length slould be 1 */
             return BUFFER_E;
 
+        /* RFC 7250 4.1, RFC 8446 4.2: the server may only answer with a type
+         * the client offered. ProcessPeerCertParse() treats the stored value as
+         * negotiated, so an unsolicited one lets the peer select RawPublicKey
+         * and skip chain verification. */
+        if (ssl->options.rpkState.sending_ServerCertTypeCnt == 0) {
+            WOLFSSL_MSG("server_cert_type received but never offered");
+            WOLFSSL_ERROR_VERBOSE(UNSUPPORTED_EXTENSION);
+            return UNSUPPORTED_EXTENSION;
+        }
+        if (!IsCertTypeListed(*input,
+                ssl->options.rpkState.sending_ServerCertTypeCnt,
+                ssl->options.rpkState.sending_ServerCertTypes)) {
+            WOLFSSL_MSG("server_cert_type value was not offered");
+            WOLFSSL_ERROR_VERBOSE(UNSUPPORTED_EXTENSION);
+            return UNSUPPORTED_EXTENSION;
+        }
+
         ssl->options.rpkState.received_ServerCertTypeCnt  = 1;
         ssl->options.rpkState.received_ServerCertTypes[0] = *input;
     }

src/x509_str.c

@@ -858,7 +858,6 @@ int wolfSSL_X509_verify_cert(WOLFSSL_X509_STORE_CTX* ctx)
 {
     int ret = WC_NO_ERR_TRACE(WOLFSSL_FAILURE);
     int done = 0;
-    int added = 0;
     int i = 0;
     int numFailedCerts = 0;
     int depth = 0;
@@ -997,11 +996,8 @@ int wolfSSL_X509_verify_cert(WOLFSSL_X509_STORE_CTX* ctx)
                     &depth, origDepth);
                 continue;
             }
-            added = 1;
             ret = X509StoreVerifyCert(ctx);
             if (ret != WOLFSSL_SUCCESS) {
-                if ((origDepth - depth) <= 1)
-                    added = 0;
                 X509VerifyCertSetupRetry(ctx, certs, failedCerts,
                     &depth, origDepth);
                 continue;
@@ -1023,21 +1019,14 @@ int wolfSSL_X509_verify_cert(WOLFSSL_X509_STORE_CTX* ctx)
                     != WOLFSSL_SUCCESS) {
                 /* Could not guarantee the temporary intermediates were
                  * dropped; fail closed rather than risk verifying the current
-                 * certificate against one.  Leave `added` set: they are still
-                 * loaded, so the exit cleanup makes a final attempt to drop
-                 * them. */
+                 * certificate against one. */
                 ret = WOLFSSL_FATAL_ERROR;
                 goto exit;
             }
-            added = 0;
             ret = X509StoreVerifyCert(ctx);
             if (ret != WOLFSSL_SUCCESS) {
                 /* WOLFSSL_PARTIAL_CHAIN may only terminate the chain at a
-                 * certificate the caller actually trusts.  The previous
-                 * "added == 1" guard merely confirmed that some untrusted
-                 * intermediate had been temporarily loaded into the
-                 * CertManager during chain building, which would accept
-                 * chains that never reach a trust anchor.  Verify that
+                 * certificate the caller actually trusts, so verify that
                  * ctx->current_cert is itself in the original trust set. */
                 if (((ctx->flags & WOLFSSL_PARTIAL_CHAIN) ||
                      (ctx->store->param != NULL &&
@@ -1149,11 +1138,17 @@ int wolfSSL_X509_verify_cert(WOLFSSL_X509_STORE_CTX* ctx)
             }
         }
     }
-    /* Remove intermediates that were added to CM */
+    /* Remove intermediates that were added to CM. Unconditional: anything left
+     * resident anchors verification for every other user of this CM. */
     if (ctx != NULL) {
         if (ctx->store != NULL) {
-            if (added == 1) {
-                wolfSSL_CertManagerUnloadTempIntermediateCerts(ctx->store->cm);
+            if (wolfSSL_CertManagerUnloadTempIntermediateCerts(ctx->store->cm)
+                    != WOLFSSL_SUCCESS) {
+                WOLFSSL_MSG("Failed to unload temporary intermediates");
+                /* Any left resident would anchor later verifications, so do
+                 * not report success. */
+                if (ret == WOLFSSL_SUCCESS)
+                    ret = WOLFSSL_FAILURE;
             }
         }
         if (orig != NULL) {
@@ -1777,13 +1772,15 @@ static void X509StoreFreeObjList(WOLFSSL_X509_STORE* store,
      * the numAdded to the store >= is used when comparing to 0. */
     i = wolfSSL_sk_X509_OBJECT_num(objs) - 1;
     while (cnt > 0 && i >= 0) {
-        /* The inner X509 is owned by somebody else, NULL out the reference */
         obj = (WOLFSSL_X509_OBJECT *)wolfSSL_sk_X509_OBJECT_value(objs, i);
-        if (obj != NULL) {
+        /* Only certificates are borrowed, so only they consume numAdded. The
+         * CRL object appended after them must not shift this window. */
+        if (obj != NULL && obj->type == WOLFSSL_X509_LU_X509) {
+            /* The inner X509 is owned by somebody else, NULL out the ref */
             obj->type = (WOLFSSL_X509_LOOKUP_TYPE)0;
             obj->data.ptr = NULL;
+            cnt--;
         }
-        cnt--;
         i--;
     }
 
@@ -2522,6 +2519,9 @@ WOLF_STACK_OF(WOLFSSL_X509_OBJECT)* wolfSSL_X509_STORE_get0_objects(
 {
     WOLFSSL_STACK* ret = NULL;
     WOLFSSL_STACK* cert_stack = NULL;
+    /* Set once the certificates have been handed over to "ret". Until then
+     * cert_stack still owns them and the error path must not free them. */
+    byte certsOwned = 0;
 #if ((defined(WOLFSSL_SIGNER_DER_CERT) && !defined(NO_FILESYSTEM)) || \
      (defined(HAVE_CRL)))
     WOLFSSL_X509_OBJECT* obj = NULL;
@@ -2595,6 +2595,7 @@ WOLF_STACK_OF(WOLFSSL_X509_OBJECT)* wolfSSL_X509_STORE_get0_objects(
     while (wolfSSL_sk_X509_num(cert_stack) > 0) {
         wolfSSL_sk_X509_pop(cert_stack);
     }
+    certsOwned = 1;
 #endif
 
 #ifdef HAVE_CRL
@@ -2625,8 +2626,28 @@ WOLF_STACK_OF(WOLFSSL_X509_OBJECT)* wolfSSL_X509_STORE_get0_objects(
     store->objs = ret;
     return ret;
 err_cleanup:
-    if (ret != NULL)
-        X509StoreFreeObjList(store, ret);
+    if (ret != NULL) {
+        if (certsOwned) {
+            X509StoreFreeObjList(store, ret);
+        }
+        else {
+            /* cert_stack still owns these certificates. pop_free() below runs
+             * wolfSSL_X509_OBJECT_free() on each entry, which frees the inner
+             * X509, so clear the references or they are freed twice. */
+            int j;
+            WOLFSSL_X509_OBJECT* cur;
+
+            for (j = 0; j < wolfSSL_sk_X509_OBJECT_num(ret); j++) {
+                cur = (WOLFSSL_X509_OBJECT*)wolfSSL_sk_X509_OBJECT_value(ret,
+                                                                         j);
+                if (cur != NULL) {
+                    cur->type = (WOLFSSL_X509_LOOKUP_TYPE)0;
+                    cur->data.ptr = NULL;
+                }
+            }
+            wolfSSL_sk_X509_OBJECT_pop_free(ret, NULL);
+        }
+    }
     if (cert_stack != NULL) {
         while (store->numAdded > 0) {
             wolfSSL_sk_X509_pop(cert_stack);

tests/api/test_dtls13.c

@@ -1122,6 +1122,45 @@ int test_dtls13_epochs(void) {
     return EXPECT_RESULT();
 }
 
+int test_dtls13_alert_with_pending_output(void)
+{
+    EXPECT_DECLS;
+#if defined(HAVE_MANUAL_MEMIO_TESTS_DEPENDENCIES) && defined(WOLFSSL_DTLS13)
+    WOLFSSL_CTX *ctx_c = NULL;
+    WOLFSSL_CTX *ctx_s = NULL;
+    WOLFSSL *ssl_c = NULL;
+    WOLFSSL *ssl_s = NULL;
+    struct test_memio_ctx test_ctx;
+    char msg[1300];
+
+    XMEMSET(&test_ctx, 0, sizeof(test_ctx));
+    XMEMSET(msg, 'A', sizeof(msg));
+
+    ExpectIntEQ(test_memio_setup(&test_ctx, &ctx_c, &ctx_s, &ssl_c, &ssl_s,
+        wolfDTLSv1_3_client_method, wolfDTLSv1_3_server_method), 0);
+    ExpectIntEQ(test_memio_do_handshake(ssl_c, ssl_s, 10, NULL), 0);
+
+    /* Stall the transport, then queue a record big enough that adding the
+     * alert would exceed the MTU. */
+    test_ctx.s_force_want_write = 1;
+    ExpectIntLT(wolfSSL_write(ssl_s, msg, (int)sizeof(msg)), 0);
+    ExpectIntGT((int)ssl_s->buffers.outputBuffer.length, 1288);
+
+    /* EndOfEarlyData is not valid in DTLS 1.3 and raises a fatal alert. */
+    ExpectIntEQ(Dtls13CheckEpoch(ssl_s, end_of_early_data), SANITY_MSG_E);
+
+    ExpectIntLE((int)(ssl_s->buffers.outputBuffer.idx +
+                      ssl_s->buffers.outputBuffer.length),
+                (int)ssl_s->buffers.outputBuffer.bufferSize);
+
+    wolfSSL_free(ssl_c);
+    wolfSSL_free(ssl_s);
+    wolfSSL_CTX_free(ctx_c);
+    wolfSSL_CTX_free(ctx_s);
+#endif
+    return EXPECT_RESULT();
+}
+
 /*-- ack_order (test_dtls.c lines 873,951) ---*/
 int test_dtls13_ack_order(void)
 {

tests/api/test_dtls13.h

@@ -44,6 +44,7 @@ int test_dtls13_basic_connection_id(void);
 int test_dtls13_hrr_want_write(void);
 int test_dtls13_every_write_want_write(void);
 int test_dtls13_epochs(void);
+int test_dtls13_alert_with_pending_output(void);
 int test_dtls13_ack_order(void);
 int test_dtls13_ack_overflow(void);
 int test_dtls13_ack_dup_write_counter(void);
@@ -71,6 +72,7 @@ int test_dtls13_reuse_after_clear(void);
     TEST_DECL_GROUP("dtls13", test_dtls13_hrr_want_write),                     \
     TEST_DECL_GROUP("dtls13", test_dtls13_every_write_want_write),             \
     TEST_DECL_GROUP("dtls13", test_dtls13_epochs),                             \
+    TEST_DECL_GROUP("dtls13", test_dtls13_alert_with_pending_output),          \
     TEST_DECL_GROUP("dtls13", test_dtls13_ack_order),                          \
     TEST_DECL_GROUP("dtls13", test_dtls13_ack_overflow),                       \
     TEST_DECL_GROUP("dtls13", test_dtls13_ack_dup_write_counter),              \