From b5678a81c8449568abfa18e326a63ee20fba651f Mon Sep 17 00:00:00 2001
From: Alexandru Geana <alex.geana@yubico.com>
Date: Thu, 30 Nov 2023 14:20:55 +0100
Subject: [PATCH] Additional buffer length checks

---
 pkcs11/util_pkcs11.c    | 37 ++++++++++++++++++++++++++-----------
 pkcs11/yubihsm_pkcs11.c |  4 ++++
 2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/pkcs11/util_pkcs11.c b/pkcs11/util_pkcs11.c
index 1112a93c..c65b7861 100644
--- a/pkcs11/util_pkcs11.c
+++ b/pkcs11/util_pkcs11.c
@@ -1080,23 +1080,34 @@ bool create_session(yubihsm_pkcs11_slot *slot, CK_FLAGS flags,
   return list_append(&slot->pkcs11_sessions, &session);
 }
 
-static void get_label_attribute(yh_object_descriptor *object, bool public,
+static CK_RV get_label_attribute(yh_object_descriptor *object, bool public,
                                 pkcs11_meta_object *meta_object,
                                 CK_VOID_PTR value, CK_ULONG_PTR length) {
   if (meta_object != NULL && !public && meta_object->cka_label.len > 0) {
+    if (*length < meta_object->cka_label.len) {
+      return CKR_HOST_MEMORY;
+    }
     *length = meta_object->cka_label.len;
     memcpy(value, meta_object->cka_label.value, *length);
   } else if (meta_object != NULL && public &&
              meta_object->cka_label_pubkey.len > 0) {
+    if (*length < meta_object->cka_label_pubkey.len) {
+      return CKR_HOST_MEMORY;
+    }
     *length = meta_object->cka_label_pubkey.len;
     memcpy(value, meta_object->cka_label_pubkey.value, *length);
   } else {
-    *length = strlen(object->label);
+    size_t label_len = strlen(object->label);
+    if (*length < label_len) {
+      return CKR_HOST_MEMORY;
+    }
+    *length = label_len;
     memcpy(value, object->label, *length);
     // NOTE(adma): we have seen some weird behvior with different
     // PKCS#11 tools. We decided not to add '\0' for now. This *seems*
     // to be a good solution ...
   }
+  return CKR_OK;
 }
 
 static void get_id_attribute(yh_object_descriptor *object, bool public,
@@ -1281,7 +1292,7 @@ static CK_RV get_attribute_opaque(CK_ATTRIBUTE_TYPE type,
       break;
 
     case CKA_LABEL:
-      get_label_attribute(object, false, meta_object, value, length);
+      return get_label_attribute(object, false, meta_object, value, length);
       break;
 
     case CKA_ID:
@@ -1362,7 +1373,7 @@ static CK_RV get_attribute_secret_key(CK_ATTRIBUTE_TYPE type,
       break;
 
     case CKA_LABEL:
-      get_label_attribute(object, false, meta_object, value, length);
+      return get_label_attribute(object, false, meta_object, value, length);
       break;
 
       // NOTE(adma): Key Objects attributes
@@ -1579,7 +1590,7 @@ static CK_RV get_attribute_private_key(CK_ATTRIBUTE_TYPE type,
       break;
 
     case CKA_LABEL:
-      get_label_attribute(object, false, meta_object, value, length);
+      return get_label_attribute(object, false, meta_object, value, length);
       break;
 
       // NOTE(adma): Key Objects attributes
@@ -2038,7 +2049,7 @@ static CK_RV get_attribute_public_key(CK_ATTRIBUTE_TYPE type,
       break;
 
     case CKA_LABEL:
-      get_label_attribute(object, true, meta_object, value, length);
+      return get_label_attribute(object, true, meta_object, value, length);
       break;
 
       // NOTE(adma): Key Objects attributes
@@ -5920,12 +5931,16 @@ CK_RV populate_template(int type, void *object, CK_ATTRIBUTE_PTR pTemplate,
                         CK_ULONG ulCount, yubihsm_pkcs11_session *session) {
 
   CK_RV rv = CKR_OK;
-#ifdef FUZZING
-  // in fuzzing builds make the data buffers smaller
-  CK_BYTE tmp[200] = {0};
-#else
+//#ifdef FUZZING
+//  /* TODO in fuzzing builds make the data buffers smaller
+//   * there are currently many locations in the code which make assumptions
+//   * that the size of the tmp buffer (and aliases) is large enough
+//   * decreasing the size now artificially will prevent the fuzzer from progressing well
+//   */
+//  CK_BYTE tmp[20] = {0};
+//#else
   CK_BYTE tmp[8192] = {0};
-#endif
+//#endif
   for (CK_ULONG i = 0; i < ulCount; i++) {
     DBG_INFO("Getting attribute 0x%lx", pTemplate[i].type);
     CK_ULONG len = sizeof(tmp);
diff --git a/pkcs11/yubihsm_pkcs11.c b/pkcs11/yubihsm_pkcs11.c
index 85c69437..72b8e769 100644
--- a/pkcs11/yubihsm_pkcs11.c
+++ b/pkcs11/yubihsm_pkcs11.c
@@ -5933,6 +5933,10 @@ CK_DEFINE_FUNCTION(CK_RV, C_DeriveKey)
   for (CK_ULONG i = 0; i < ulAttributeCount; i++) {
     switch (pTemplate[i].type) {
       case CKA_VALUE_LEN:
+        if (pTemplate[i].ulValueLen < sizeof(CK_ULONG)) {
+          rv = CKR_ATTRIBUTE_VALUE_INVALID;
+          goto c_drv_out;
+        }
         value_len = *((CK_ULONG *) pTemplate[i].pValue);
         break;
       case CKA_LABEL: