Avoid reading outside a record buffer when extracting an SQL value in the sqlite_dbdata virtual table code.

FossilOrigin-Name: d99bb0c11d62f629bf59da037827af73a9b814e65815006e0cbca1bc41f42e25

ext/misc/dbdata.c

@@ -382,7 +382,10 @@ static int dbdataValueBytes(int eType){
     case 7:
       return 8;
     default:
-      return ((eType-12) / 2);
+      if( eType>0 ){
+        return ((eType-12) / 2);
+      }
+      return 0;
   }
 }
 
@@ -390,55 +393,61 @@ static int dbdataValueBytes(int eType){
 ** Load a value of type eType from buffer pData and use it to set the
 ** result of context object pCtx.
 */
-static void dbdataValue(sqlite3_context *pCtx, int eType, u8 *pData){
-  switch( eType ){
-    case 0: 
-    case 10: 
-    case 11: 
-      sqlite3_result_null(pCtx);
-      break;
+static void dbdataValue(
+  sqlite3_context *pCtx, 
+  int eType, 
+  u8 *pData,
+  int nData
+){
+  if( eType>=0 && dbdataValueBytes(eType)<=nData ){
+    switch( eType ){
+      case 0: 
+      case 10: 
+      case 11: 
+        sqlite3_result_null(pCtx);
+        break;
       
-    case 8: 
-      sqlite3_result_int(pCtx, 0);
-      break;
-    case 9:
-      sqlite3_result_int(pCtx, 1);
-      break;
+      case 8: 
+        sqlite3_result_int(pCtx, 0);
+        break;
+      case 9:
+        sqlite3_result_int(pCtx, 1);
+        break;
   
-    case 1: case 2: case 3: case 4: case 5: case 6: case 7: {
-      sqlite3_uint64 v = (signed char)pData[0];
-      pData++;
-      switch( eType ){
-        case 7:
-        case 6:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
-        case 5:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
-        case 4:  v = (v<<8) + pData[0];  pData++;
-        case 3:  v = (v<<8) + pData[0];  pData++;
-        case 2:  v = (v<<8) + pData[0];  pData++;
+      case 1: case 2: case 3: case 4: case 5: case 6: case 7: {
+        sqlite3_uint64 v = (signed char)pData[0];
+        pData++;
+        switch( eType ){
+          case 7:
+          case 6:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
+          case 5:  v = (v<<16) + (pData[0]<<8) + pData[1];  pData += 2;
+          case 4:  v = (v<<8) + pData[0];  pData++;
+          case 3:  v = (v<<8) + pData[0];  pData++;
+          case 2:  v = (v<<8) + pData[0];  pData++;
+        }
+  
+        if( eType==7 ){
+          double r;
+          memcpy(&r, &v, sizeof(r));
+          sqlite3_result_double(pCtx, r);
+        }else{
+          sqlite3_result_int64(pCtx, (sqlite3_int64)v);
+        }
+        break;
       }
   
-      if( eType==7 ){
-        double r;
-        memcpy(&r, &v, sizeof(r));
-        sqlite3_result_double(pCtx, r);
-      }else{
-        sqlite3_result_int64(pCtx, (sqlite3_int64)v);
-      }
-      break;
-    }
-
-    default: {
-      int n = ((eType-12) / 2);
-      if( eType % 2 ){
-        sqlite3_result_text(pCtx, (const char*)pData, n, SQLITE_TRANSIENT);
-      }else{
-        sqlite3_result_blob(pCtx, pData, n, SQLITE_TRANSIENT);
+      default: {
+        int n = ((eType-12) / 2);
+        if( eType % 2 ){
+          sqlite3_result_text(pCtx, (const char*)pData, n, SQLITE_TRANSIENT);
+        }else{
+          sqlite3_result_blob(pCtx, pData, n, SQLITE_TRANSIENT);
+        }
       }
     }
   }
 }
 
-
 /*
 ** Move an sqlite_dbdata or sqlite_dbptr cursor to the next entry.
 */
@@ -728,7 +737,9 @@ static int dbdataColumn(
         }else{
           sqlite3_int64 iType;
           dbdataGetVarint(pCsr->pHdrPtr, &iType);
-          dbdataValue(ctx, iType, pCsr->pPtr);
+          dbdataValue(
+              ctx, iType, pCsr->pPtr, &pCsr->pRec[pCsr->nRec] - pCsr->pPtr
+          );
         }
         break;
       }

manifest

@@ -1,5 +1,5 @@
-C Merge\saccidental\sfork\sin\strunk.
-D 2019-05-09T11:21:32.067
+C Avoid\sreading\soutside\sa\srecord\sbuffer\swhen\sextracting\san\sSQL\svalue\sin\sthe\ssqlite_dbdata\svirtual\stable\scode.
+D 2019-05-09T11:34:31.409
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -284,7 +284,7 @@ F ext/misc/closure.c dbfd8543b2a017ae6b1a5843986b22ddf99ff126ec9634a2f4047cd14c8
 F ext/misc/completion.c cec672d40604075bb341a7f11ac48393efdcd90a979269b8fe7977ea62d0547f
 F ext/misc/compress.c dd4f8a6d0baccff3c694757db5b430f3bbd821d8686d1fc24df55cf9f035b189
 F ext/misc/csv.c 7f047aeb68f5802e7ce6639292095d622a488bb43526ed04810e0649faa71ceb
-F ext/misc/dbdata.c 1b3751b02d8f575d25c6bda358670d2e39ace368a0d05595989c308a10c615f6
+F ext/misc/dbdata.c 1d3d1ebd23d3e4e5debbc54719376781e146626c2ee0b989b412b1a9c8ccdd37
 F ext/misc/dbdump.c baf6e37447c9d6968417b1cd34cbedb0b0ab3f91b5329501d8a8d5be3287c336
 F ext/misc/eval.c 4b4757592d00fd32e44c7a067e6a0e4839c81a4d57abc4131ee7806d1be3104e
 F ext/misc/explain.c d5c12962d79913ef774b297006872af1fccda388f61a11d37758f9179a09551f
@@ -1825,8 +1825,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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-R 1ba7996ce03dd9a1187260e95804fc29
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 U dan
-Z e19c180b1a7fc00850ba36320f2fd4c8
+Z f6d6e605cd200b1a74018499a0dcfaa6

manifest.uuid

@@ -1 +1 @@
-ec9373031d76b34163a45d0ed05e43c0c9d585c8d47aa255f670340673bc7875
+d99bb0c11d62f629bf59da037827af73a9b814e65815006e0cbca1bc41f42e25