From f735ea7b0d1193bc6c9e8877ca2a04e92474baad Mon Sep 17 00:00:00 2001
From: Marcel Peterkau <marcel@peterkau.de>
Date: Sun, 24 Aug 2025 13:31:27 +0200
Subject: [PATCH] hardened EEPROM against out of Bounds and garbage in RAM

---
 Software/src/config.cpp | 58 ++++++++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 18 deletions(-)

diff --git a/Software/src/config.cpp b/Software/src/config.cpp
index 1dc6652..c451ef7 100644
--- a/Software/src/config.cpp
+++ b/Software/src/config.cpp
@@ -283,9 +283,8 @@ void StoreConfig_EEPROM()
 /**
  * @brief Load configuration from EEPROM and validate.
  *
- * Performs CRC check and sanity validation and raises the respective DTCs:
- * - DTC_EEPROM_CFG_BAD if CRC fails
- * - DTC_EEPROM_CFG_SANITY with bitmask payload if values are out of bounds
+ * On CRC failure: raise DTC_EEPROM_CFG_BAD and fall back to in-RAM defaults (no writes).
+ * On CRC OK: run sanity with autocorrect=true and raise DTC_EEPROM_CFG_SANITY with bitmask if needed.
  */
 void GetConfig_EEPROM()
 {
@@ -297,12 +296,20 @@ void GetConfig_EEPROM()
   const uint32_t checksum = LubeConfig.checksum;
   LubeConfig.checksum = 0;
 
-  MaintainDTC(DTC_EEPROM_CFG_BAD,
-              (Checksum_EEPROM((uint8_t *)&LubeConfig, sizeof(LubeConfig)) != checksum));
+  const bool badCrc = (Checksum_EEPROM((uint8_t *)&LubeConfig, sizeof(LubeConfig)) != checksum);
+  MaintainDTC(DTC_EEPROM_CFG_BAD, badCrc);
 
+  if (badCrc) {
+    // Don’t keep corrupted data in RAM
+    LubeConfig = LubeConfig_defaults;
+    LubeConfig.EEPROM_Version = EEPROM_STRUCTURE_REVISION; // explicit in-RAM version
+    return;
+  }
+
+  // CRC OK → restore checksum and sanitize (with autocorrect)
   LubeConfig.checksum = checksum;
 
-  const uint32_t sanity = ConfigSanityCheck(false);
+  const uint32_t sanity = ConfigSanityCheck(true);
   MaintainDTC(DTC_EEPROM_CFG_SANITY, (sanity > 0), sanity);
 }
 
@@ -333,33 +340,48 @@ void StorePersistence_EEPROM()
  *
  * If the stored start address is out of range, the persistence partition is reset,
  * formatted, and DTC_EEPROM_PDSADRESS_BAD is raised.
- * Otherwise, the record is read and checked; DTC_EEPROM_PDS_BAD is raised on CRC failure.
+ * Otherwise, the record is read and checked; on CRC failure DTC_EEPROM_PDS_BAD is raised
+ * and the in-RAM persistence data is reset to a safe default (no writes performed here).
  */
 void GetPersistence_EEPROM()
 {
   if (!EEPROM_Available())
     return;
 
+  // Read wear-level start address
   ee.readBlock(0, (uint8_t *)&globals.eePersistenceAddress, sizeof(globals.eePersistenceAddress));
 
-  if (globals.eePersistenceAddress < startofPersistence || globals.eePersistenceAddress > ee.getDeviceSize())
+  const uint16_t addr = globals.eePersistenceAddress;
+  const uint16_t need = sizeof(PersistenceData);
+  const uint16_t dev = ee.getDeviceSize();
+
+  // Strict range check: addr must be within partition and block must fit into device
+  if (addr < startofPersistence || (uint32_t)addr + (uint32_t)need > (uint32_t)dev)
   {
     MovePersistencePage_EEPROM(true);
     FormatPersistence_EEPROM();
     MaintainDTC(DTC_EEPROM_PDSADRESS_BAD, true);
+    return;
   }
-  else
+
+  // Safe to read the record
+  ee.readBlock(addr, (uint8_t *)&PersistenceData, sizeof(PersistenceData));
+
+  const uint32_t checksum = PersistenceData.checksum;
+  PersistenceData.checksum = 0;
+
+  const bool badCrc = (Checksum_EEPROM((uint8_t *)&PersistenceData, sizeof(PersistenceData)) != checksum);
+  MaintainDTC(DTC_EEPROM_PDS_BAD, badCrc);
+
+  if (badCrc)
   {
-    ee.readBlock(globals.eePersistenceAddress, (uint8_t *)&PersistenceData, sizeof(PersistenceData));
-
-    const uint32_t checksum = PersistenceData.checksum;
-    PersistenceData.checksum = 0;
-
-    MaintainDTC(DTC_EEPROM_PDS_BAD,
-                (Checksum_EEPROM((uint8_t *)&PersistenceData, sizeof(PersistenceData)) != checksum));
-
-    PersistenceData.checksum = checksum;
+    // Do not keep corrupted data in RAM; leave DTC set, no EEPROM writes here
+    PersistenceData = {0};
+    return;
   }
+
+  // CRC ok -> restore checksum into the struct kept in RAM
+  PersistenceData.checksum = checksum;
 }
 
 /**