Index: ext/rtree/rtree.c
==================================================================
--- ext/rtree/rtree.c
+++ ext/rtree/rtree.c
@@ -126,10 +126,13 @@
   u8 eCoordType;              /* RTREE_COORD_REAL32 or RTREE_COORD_INT32 */
   u8 nBytesPerCell;           /* Bytes consumed per cell */
   u8 inWrTrans;               /* True if inside write transaction */
   u8 nAux;                    /* # of auxiliary columns in %_rowid */
   u8 nAuxNotNull;             /* Number of initial not-null aux columns */
+#ifdef SQLITE_DEBUG
+  u8 bCorrupt;                /* Shadow table corruption detected */
+#endif
   int iDepth;                 /* Current depth of the r-tree structure */
   char *zDb;                  /* Name of database containing r-tree table */
   char *zName;                /* Name of r-tree table */ 
   u32 nBusy;                  /* Current number of users of this structure */
   i64 nRowEst;                /* Estimated number of rows in this table */
@@ -185,10 +188,19 @@
   typedef double RtreeDValue;              /* High accuracy coordinate */
   typedef float RtreeValue;                /* Low accuracy coordinate */
 # define RTREE_ZERO 0.0
 #endif
 
+/*
+** Set the Rtree.bCorrupt flag
+*/
+#ifdef SQLITE_DEBUG
+# define RTREE_IS_CORRUPT(X) ((X)->bCorrupt = 1)
+#else
+# define RTREE_IS_CORRUPT(X)
+#endif
+
 /*
 ** When doing a search of an r-tree, instances of the following structure
 ** record intermediate results from the tree walk.
 **
 ** The id is always a node-id.  For iLevel>=1 the id is the node-id of
@@ -669,11 +681,14 @@
   if( rc ){
     nodeBlobReset(pRtree);
     *ppNode = 0;
     /* If unable to open an sqlite3_blob on the desired row, that can only
     ** be because the shadow tables hold erroneous data. */
-    if( rc==SQLITE_ERROR ) rc = SQLITE_CORRUPT_VTAB;
+    if( rc==SQLITE_ERROR ){
+      rc = SQLITE_CORRUPT_VTAB;
+      RTREE_IS_CORRUPT(pRtree);
+    }
   }else if( pRtree->iNodeSize==sqlite3_blob_bytes(pRtree->pNodeBlob) ){
     pNode = (RtreeNode *)sqlite3_malloc(sizeof(RtreeNode)+pRtree->iNodeSize);
     if( !pNode ){
       rc = SQLITE_NOMEM;
     }else{
@@ -698,10 +713,11 @@
   */
   if( pNode && iNode==1 ){
     pRtree->iDepth = readInt16(pNode->zData);
     if( pRtree->iDepth>RTREE_MAX_DEPTH ){
       rc = SQLITE_CORRUPT_VTAB;
+      RTREE_IS_CORRUPT(pRtree);
     }
   }
 
   /* If no error has occurred so far, check if the "number of entries"
   ** field on the node is too large. If so, set the return code to 
@@ -708,18 +724,20 @@
   ** SQLITE_CORRUPT_VTAB.
   */
   if( pNode && rc==SQLITE_OK ){
     if( NCELL(pNode)>((pRtree->iNodeSize-4)/pRtree->nBytesPerCell) ){
       rc = SQLITE_CORRUPT_VTAB;
+      RTREE_IS_CORRUPT(pRtree);
     }
   }
 
   if( rc==SQLITE_OK ){
     if( pNode!=0 ){
       nodeHashInsert(pRtree, pNode);
     }else{
       rc = SQLITE_CORRUPT_VTAB;
+      RTREE_IS_CORRUPT(pRtree);
     }
     *ppNode = pNode;
   }else{
     if( pNode ){
       pRtree->nNodeRef--;
@@ -941,11 +959,11 @@
   pRtree->nBusy--;
   if( pRtree->nBusy==0 ){
     pRtree->inWrTrans = 0;
     assert( pRtree->nCursor==0 );
     nodeBlobReset(pRtree);
-    assert( pRtree->nNodeRef==0 );
+    assert( pRtree->nNodeRef==0 || pRtree->bCorrupt );
     sqlite3_finalize(pRtree->pWriteNode);
     sqlite3_finalize(pRtree->pDeleteNode);
     sqlite3_finalize(pRtree->pReadRowid);
     sqlite3_finalize(pRtree->pWriteRowid);
     sqlite3_finalize(pRtree->pDeleteRowid);
@@ -1273,10 +1291,11 @@
     if( nodeGetRowid(pRtree, pNode, ii)==iRowid ){
       *piIndex = ii;
       return SQLITE_OK;
     }
   }
+  RTREE_IS_CORRUPT(pRtree);
   return SQLITE_CORRUPT_VTAB;
 }
 
 /*
 ** Return the index of the cell containing a pointer to node pNode
@@ -2135,16 +2154,18 @@
   Rtree *pRtree,                    /* Rtree table */
   RtreeNode *pNode,                 /* Adjust ancestry of this node. */
   RtreeCell *pCell                  /* This cell was just inserted */
 ){
   RtreeNode *p = pNode;
+  int cnt = 0;
   while( p->pParent ){
     RtreeNode *pParent = p->pParent;
     RtreeCell cell;
     int iCell;
 
-    if( nodeParentIndex(pRtree, p, &iCell) ){
+    if( (++cnt)>1000 || nodeParentIndex(pRtree, p, &iCell)  ){
+      RTREE_IS_CORRUPT(pRtree);
       return SQLITE_CORRUPT_VTAB;
     }
 
     nodeGetCell(pRtree, pParent, iCell, &cell);
     if( !cellContains(pRtree, &cell, pCell) ){
@@ -2608,11 +2629,14 @@
         rc2 = nodeAcquire(pRtree, iNode, 0, &pChild->pParent);
       }
     }
     rc = sqlite3_reset(pRtree->pReadParent);
     if( rc==SQLITE_OK ) rc = rc2;
-    if( rc==SQLITE_OK && !pChild->pParent ) rc = SQLITE_CORRUPT_VTAB;
+    if( rc==SQLITE_OK && !pChild->pParent ){
+      RTREE_IS_CORRUPT(pRtree);
+      rc = SQLITE_CORRUPT_VTAB;
+    }
     pChild = pChild->pParent;
   }
   return rc;
 }
 
@@ -3557,10 +3581,11 @@
     rc = getIntFromStmt(db, zSql, &pRtree->iNodeSize);
     if( rc!=SQLITE_OK ){
       *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
     }else if( pRtree->iNodeSize<(512-64) ){
       rc = SQLITE_CORRUPT_VTAB;
+      RTREE_IS_CORRUPT(pRtree);
       *pzErr = sqlite3_mprintf("undersize RTree blobs in \"%q_node\"",
                                pRtree->zName);
     }
   }
 

Index: ext/rtree/rtreefuzz001.test
==================================================================
--- ext/rtree/rtreefuzz001.test
+++ ext/rtree/rtreefuzz001.test
@@ -20,13 +20,10 @@
   finish_test
   return
 }
 database_may_be_corrupt
 
-# In the following database file, there is 384 bytes of free space
-# on page 8 that does not appear on the freeblock list.
-#
 do_test rtreefuzz001-100 {
   sqlite3 db {}
   db deserialize [decode_hexdb {
 | size 24576 pagesize 4096 filename c1b.db
 | page 1 offset 0
@@ -470,6 +467,105 @@
   catchsql {
      SELECT rtreecheck('t1');
   }
 } {1 {SQL logic error}}
 
+do_test rtreefuzz001-200 {
+  sqlite3 db {}
+  db deserialize [decode_hexdb {
+.open --hexdb
+| size 16384 pagesize 4096 filename c3.db
+| page 1 offset 0
+|      0: 53 51 4c 69 74 65 20 66 6f 72 6d 61 74 20 33 00   SQLite format 3.
+|     16: 10 00 01 01 00 40 20 20 00 00 00 00 00 00 00 04   .....@  ........
+|     32: 00 00 00 00 01 00 00 00 00 00 00 04 00 00 00 04   ................
+|     48: 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00   ................
+|     96: 00 00 00 00 0d 00 00 00 04 0e 9c 00 0f ad 0f 4f   ...............O
+|    112: 0e fc 0e 9c 00 00 00 00 00 00 00 00 00 00 00 00   ................
+|   3728: 00 00 00 00 00 00 00 00 00 00 00 00 5e 04 07 17   ............^...
+|   3744: 1f 1f 01 81 0b 74 61 62 6c 65 74 31 5f 70 61 72   .....tablet1_par
+|   3760: 65 6e 74 74 31 5f 70 61 72 65 6e 74 04 43 52 45   entt1_parent.CRE
+|   3776: 41 54 45 20 54 41 42 4c 45 20 22 74 31 5f 70 61   ATE TABLE "t1_pa
+|   3792: 72 65 6e 74 22 28 6e 6f 64 65 6e 6f 20 49 4e 54   rent"(nodeno INT
+|   3808: 45 47 45 52 20 50 52 49 4d 41 52 59 20 4b 45 59   EGER PRIMARY KEY
+|   3824: 2c 70 61 72 65 6e 74 6e 6f 64 65 29 51 03 06 17   ,parentnode)Q...
+|   3840: 1b 1b 01 7b 74 61 62 6c 65 74 31 5f 6e 6f 64 65   ....tablet1_node
+|   3856: 74 31 5f 6e 6f 64 65 03 43 52 45 41 54 45 20 54   t1_node.CREATE T
+|   3872: 41 42 4c 45 20 22 74 31 5f 6e 6f 64 65 22 28 6e   ABLE "t1_node"(n
+|   3888: 6f 64 65 6e 6f 20 49 4e 54 45 47 45 52 20 50 52   odeno INTEGER PR
+|   3904: 49 4d 41 52 59 20 4b 45 59 2c 64 61 74 61 29 5c   IMARY KEY,data)\
+|   3920: 02 07 17 1d 1d 01 81 0b 74 61 62 6c 65 74 31 5f   ........tablet1_
+|   3936: 72 6f 77 69 64 74 31 5f 72 6f 77 69 64 02 43 52   rowidt1_rowid.CR
+|   3952: 45 41 54 45 20 54 41 42 4c 45 20 22 74 31 5f 72   EATE TABLE "t1_r
+|   3968: 6f 77 69 64 22 28 72 6f 77 69 64 20 49 4e 54 45   owid"(rowid INTE
+|   3984: 47 45 52 20 50 52 49 4d 41 52 59 20 4b 45 59 2c   GER PRIMARY KEY,
+|   4000: 6e 6f 64 65 6e 6f 2c 61 30 2c 61 31 29 51 01 07   nodeno,a0,a1)Q..
+|   4016: 17 11 11 08 81 0f 74 61 62 6c 65 74 31 74 31 43   ......tablet1t1C
+|   4032: 52 45 41 54 45 20 56 49 52 54 55 41 4c 20 54 41   REATE VIRTUAL TA
+|   4048: 42 4c 45 20 74 31 20 55 53 49 4e 47 20 72 74 72   BLE t1 USING rtr
+|   4064: 65 65 28 69 64 2c 78 30 2c 78 31 2c 79 30 2c 79   ee(id,x0,x1,y0,y
+|   4080: 31 2c 2b 6c 61 62 65 6c 2c 2b 6f 74 68 65 72 29   1,+label,+other)
+| page 2 offset 4096
+|      0: 0d 00 00 00 0e 0e f7 00 0f e8 0f d0 0f b7 0f 9e   ................
+|     16: 0f 91 0f 81 0f 70 0f 5e 0f 4f 0f 39 0f 29 0f 18   .....p.^.O.9.)..
+|     32: 0f 06 0e f7 00 00 00 00 00 00 00 00 00 00 00 00   ................
+|   3824: 00 00 00 00 00 00 00 0d 0e 05 00 09 1d 00 74 6f   ..............to
+|   3840: 70 20 68 61 6c 66 10 0d 05 00 09 23 00 62 6f 74   p half.....#.bot
+|   3856: 74 6f 6d 20 68 61 6c 66 0f 0c 05 00 09 21 00 72   tom half.....!.r
+|   3872: 69 67 68 74 20 68 61 6c 66 0e 0b 05 00 09 1f 00   ight half.......
+|   3888: 6c 65 66 74 20 68 61 6c 66 14 0a 05 00 09 2b 00   left half.....+.
+|   3904: 74 68 65 20 77 68 6f 6c 65 20 74 68 69 6e 67 0d   the whole thing.
+|   3920: 09 05 00 09 1d 00 74 6f 70 20 65 64 67 65 10 08   ......top edge..
+|   3936: 05 00 09 23 00 62 6f 74 74 6f 6d 20 65 64 67 65   ...#.bottom edge
+|   3952: 0f 07 05 00 09 21 00 72 69 67 68 74 20 65 64 67   .....!.right edg
+|   3968: 65 0e 06 05 00 09 1f 00 6c 65 66 74 20 65 64 67   e.......left edg
+|   3984: 65 0b 05 05 00 09 19 00 63 65 6e 74 65 72 17 04   e.......center..
+|   4000: 05 00 09 31 00 75 70 70 65 72 2d 72 69 67 68 74   ...1.upper-right
+|   4016: 20 63 6f 72 6e 65 72 17 03 05 00 09 31 00 6c 6f    corner.....1.lo
+|   4032: 77 65 72 2d 72 69 67 68 74 27 60 f6 32 6e 65 72   wer-right'`.2ner
+|   4048: 16 02 05 00 09 2f 00 75 70 70 65 72 2d 6c 65 66   ...../.upper-lef
+|   4064: 74 20 63 6f 72 6e 65 72 16 01 05 00 09 2f 00 6c   t corner...../.l
+|   4080: 6f 77 65 72 2d 6c 65 66 74 20 63 6f 72 6e 65 72   ower-left corner
+| page 3 offset 8192
+|      0: 0d 00 00 00 02 0b 2d 00 0b 2d 00 00 00 00 00 00   ......-..-......
+|   2848: 00 00 00 00 00 00 00 00 00 00 00 00 00 89 50 01   ..............P.
+|   2864: 04 00 93 24 00 00 00 0e 00 00 00 00 00 00 00 01   ...$............
+|   2880: 00 00 00 00 41 20 00 00 00 00 00 00 41 20 01 00   ....A ......A ..
+|   2896: 00 00 00 00 00 00 00 02 00 00 00 00 41 00 00 04   ............A...
+|   2912: 2b 40 00 0c 42 c8 00 00 00 00 00 00 00 00 00 03   +@..B...........
+|   2928: 42 b4 00 00 42 c8 00 00 00 00 00 00 41 20 00 00   B...B.......A ..
+|   2944: 00 00 00 00 00 00 00 04 42 b4 00 00 42 c8 00 00   ........B...B...
+|   2960: 42 b4 00 00 42 c8 00 00 00 00 00 00 00 00 00 05   B...B...........
+|   2976: 42 20 00 00 42 70 00 00 42 20 00 00 42 70 00 00   B ..Bp..B ..Bp..
+|   2992: 00 00 00 00 00 00 00 60 00 00 00 04 0a 00 00 00   .......`........
+|   3008: 00 00 00 42 c8 00 00 00 00 00 00 00 00 00 07 42   ...B...........B
+|   3024: be 00 00 42 c8 00 00 00 00 00 00 42 c8 00 00 00   ...B.......B....
+|   3040: 00 00 00 00 00 00 08 00 00 00 00 42 c8 00 00 00   ...........B....
+|   3056: 00 00 00 40 a0 00 00 00 00 00 00 00 00 00 09 00   ...@............
+|   3072: 00 00 00 42 c8 00 00 42 be 00 00 42 c8 00 00 00   ...B...B...B....
+|   3088: 00 00 00 00 00 00 0a 00 00 00 00 42 c8 00 00 00   ...........B....
+|   3104: 00 00 00 42 c8 00 00 00 00 00 00 00 00 00 0b 00   ...B............
+|   3120: 00 00 00 42 48 00 00 00 00 00 04 2c 80 00 00 00   ...BH......,....
+|   3136: 00 00 00 00 00 00 c4 24 c0 00 04 2c 80 00 00 00   .......$...,....
+|   3152: 00 00 04 2c 80 00 00 00 00 00 00 00 00 00 d0 00   ...,............
+|   3168: 00 00 04 2c 80 00 00 00 00 00 04 24 80 00 00 00   ...,.......$....
+|   3184: 00 00 00 00 00 00 e0 00 00 00 04 2c 80 00 04 24   ...........,...$
+|   3200: c0 00 04 2c 00 00 00 00 00 00 00 00 00 00 00 00   ...,............
+| page 4 offset 12288
+|      0: 0d 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00   ................
+| end c3.db
+  }]
+  catchsql {
+    WITH RECURSIVE
+      c1(x) AS (VALUES(0) UNION ALL SELECT x+1 FROM c1 WHERE x<99),
+      c2(y) AS (VALUES(0) UNION ALL SELECT y+1 FROM c2 WHERE y<99)
+    INSERT INTO t1(id, x0,x1,y0,y1,label)
+      SELECT 1000+x+y*100, x, x+1, y, y+1, printf('box-%d,%d',x,y) FROM c1, c2;
+  }
+} {1 {malformed database schema (?)}}
+do_test rtreefuzz001-210 {
+  catchsql {
+    SELECT rtreecheck('t1');
+  }
+} {1 {database disk image is malformed}}
+
 finish_test