tx_pool: fix infinite loop when failing to find a meta record

src/cryptonote_core/tx_pool.cpp

@@ -1140,7 +1140,7 @@ namespace cryptonote
     LockedTXN lock(m_blockchain);
 
     auto sorted_it = m_txs_by_fee_and_receive_time.begin();
-    while (sorted_it != m_txs_by_fee_and_receive_time.end())
+    for (; sorted_it != m_txs_by_fee_and_receive_time.end(); ++sorted_it)
     {
       txpool_tx_meta_t meta;
       if (!m_blockchain.get_txpool_tx_meta(sorted_it->second, meta))
@@ -1154,7 +1154,6 @@ namespace cryptonote
       if (max_total_size < total_size + meta.blob_size)
       {
         LOG_PRINT_L2("  would exceed maximum block size");
-        sorted_it++;
         continue;
       }
 
@@ -1167,14 +1166,12 @@ namespace cryptonote
         if(!get_block_reward(median_size, total_size + meta.blob_size, already_generated_coins, block_reward, version))
         {
           LOG_PRINT_L2("  would exceed maximum block size");
-          sorted_it++;
           continue;
         }
         coinbase = block_reward + fee + meta.fee;
         if (coinbase < template_accept_threshold(best_coinbase))
         {
           LOG_PRINT_L2("  would decrease coinbase to " << print_money(coinbase));
-          sorted_it++;
           continue;
         }
       }
@@ -1221,13 +1218,11 @@ namespace cryptonote
       if (!ready)
       {
         LOG_PRINT_L2("  not ready to go");
-        sorted_it++;
         continue;
       }
       if (have_key_images(k_images, tx))
       {
         LOG_PRINT_L2("  key images already seen");
-        sorted_it++;
         continue;
       }
 
@@ -1236,7 +1231,6 @@ namespace cryptonote
       fee += meta.fee;
       best_coinbase = coinbase;
       append_key_images(k_images, tx);
-      sorted_it++;
       LOG_PRINT_L2("  added, new block size " << total_size << "/" << max_total_size << ", coinbase " << print_money(best_coinbase));
     }