city_create_unit() segfaults when punit is null

• 回報者: (匿名)
• 負責人: cazfi
• 類型: 修補檔案
• 狀態: 關閉
• 元件: Server
• 里程碑: 3.1.0-beta3 (closed)
• 優先權: 5 - 中
• 嚴重程度: 5 - 中
• 處理結果: 修正
• 檔案: 1

細節

This wasn't caught before because it's very rare. However, there may be ways to get units which are null in some situations like multiple build slots, etc. FCW server experienced it and had to fix it.

 static struct unit *city_create_unit(struct city *pcity,
                                      const struct unit_type *utype)
 {
   if (!pcity || !utype) return NULL;   // 17Oct2022 attempt to avoid segfault
 
   struct player *pplayer = city_owner(pcity);
   struct unit *punit;
   int saved_unit_id;
                       city_production_unit_veteran_level(pcity, utype),
                       pcity->id, 0);
   pplayer->score.units_built++;
   if (!punit) {
           notify_conn(game.est_connections, city_tile(pcity),
                   E_WONDER_WILL_BE_BUILT, ftc_server,
                   _("Notice: %s in %s creating illegal segfault. Report to admin immediately!"),
                   utype_name_translation(utype), 
                   city_link(pcity));
     return NULL;              // 17Oct2022 line below was segfault:
   }
   saved_unit_id = punit->id;

Ticket History (3/5 Histories)

2022-10-17 20:58 Updated by: None

• New Ticket "city_create_unit() segfaults when punit is null" created

2022-10-17 21:35 Updated by: cazfi

評語

Reply To (Anonymous)

This wasn't caught before because it's very rare. However, there may be ways to get units which are null in some situations like multiple build slots, etc. FCW server experienced it and had to fix it.

Those cases with multiple build slots producing NULL units seem like result of FCW specific bugs #45894 and #45895

2023-06-09 07:34 Updated by: cazfi

• File 0033-Give-city_create_unit-parameters-nonnull-attribute.patch (File ID: 12609) is attached

2023-06-09 07:36 Updated by: cazfi

• 負責人 Update from (無) to cazfi
• 處理結果 Update from 無 to Accepted
• 里程碑 Update from (無) to 3.1.0-beta3 (closed)
• 元件 Update from (無) to Server
• 類型 Update from 問題回報 to 修補檔案

評語

Reply To cazfi

Those cases with multiple build slots producing NULL units seem like result of FCW specific bugs #45894 and #45895

Attached patch gives those parameters nonnull attribute, to make it likely that in the future such bugs get caught as soon as they get created.

2023-06-12 03:23 Updated by: cazfi

• 狀態 Update from 開啟 to 關閉
• 處理結果 Update from Accepted to 修正