fix a couple bugs found by OSS-fuzz

- index out of bounds when importing outputs
- accessing invalid CLSAG data

src/ringct/rctTypes.h

@@ -368,6 +368,12 @@ namespace rct {
         template<bool W, template <bool> class Archive>
         bool serialize_rctsig_prunable(Archive<W> &ar, uint8_t type, size_t inputs, size_t outputs, size_t mixin)
         {
+          if (inputs >= 0xffffffff)
+            return false;
+          if (outputs >= 0xffffffff)
+            return false;
+          if (mixin >= 0xffffffff)
+            return false;
           if (type == RCTTypeNull)
             return ar.stream().good();
           if (type != RCTTypeFull && type != RCTTypeSimple && type != RCTTypeBulletproof && type != RCTTypeBulletproof2 && type != RCTTypeCLSAG)

src/wallet/wallet2.cpp

@@ -13043,6 +13043,8 @@ process:
     crypto::public_key tx_pub_key = get_tx_pub_key_from_received_outs(td);
     const std::vector<crypto::public_key> additional_tx_pub_keys = get_additional_tx_pub_keys_from_extra(td.m_tx);
 
+    THROW_WALLET_EXCEPTION_IF(td.m_internal_output_index >= td.m_tx.vout.size(),
+        error::wallet_internal_error, "Internal index is out of range");
     THROW_WALLET_EXCEPTION_IF(td.m_tx.vout[td.m_internal_output_index].target.type() != typeid(cryptonote::txout_to_key),
         error::wallet_internal_error, "Unsupported output type");
     const crypto::public_key& out_key = boost::get<cryptonote::txout_to_key>(td.m_tx.vout[td.m_internal_output_index].target).key;