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Overview
Comment:Back out the expansion of the temporary buffer size from [32754ca6f86da816] and replace it with an explicit test for buffer overreads.
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SHA3-256: 8ba3d9f38090c4bbbcffba1930e5c26f69ff61f49b72a4a5a59253d37341380f
User & Date: drh 2018-12-14 16:20:54
Context
2018-12-14
17:57
Fix possible integer overflow while running PRAGMA integrity_check on a database file with a badly corrupted freelist. check-in: 39559911 user: drh tags: trunk
16:20
Back out the expansion of the temporary buffer size from [32754ca6f86da816] and replace it with an explicit test for buffer overreads. check-in: 8ba3d9f3 user: drh tags: trunk
16:00
Avoid a buffer overread in ptrmapPutOvflPtr() that can occurs in a corrupt database file that has large entries and uses autovacuum. check-in: f8b781cf user: drh tags: trunk
Changes
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Changes to src/btree.c.

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  i = get2byte(&aData[hdr+5]);
  memcpy(&pTmp[i], &aData[i], usableSize - i);

  pData = pEnd;
  for(i=0; i<nCell; i++){
    u8 *pCell = apCell[i];
    if( SQLITE_WITHIN(pCell,aData,pEnd) ){

      pCell = &pTmp[pCell - aData];
    }
    pData -= szCell[i];
    put2byte(pCellptr, (pData - aData));
    pCellptr += 2;
    if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
    memcpy(pData, pCell, szCell[i]);







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  i = get2byte(&aData[hdr+5]);
  memcpy(&pTmp[i], &aData[i], usableSize - i);

  pData = pEnd;
  for(i=0; i<nCell; i++){
    u8 *pCell = apCell[i];
    if( SQLITE_WITHIN(pCell,aData,pEnd) ){
      if( ((uptr)(pCell+szCell[i]))>(uptr)pEnd ) return SQLITE_CORRUPT_BKPT;
      pCell = &pTmp[pCell - aData];
    }
    pData -= szCell[i];
    put2byte(pCellptr, (pData - aData));
    pCellptr += 2;
    if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
    memcpy(pData, pCell, szCell[i]);

Changes to src/pcache1.c.

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** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/
void *sqlite3PageMalloc(int sz){
  /* During rebalance operations on a corrupt database file, it is sometimes
  ** (rarely) possible to overread the temporary page buffer by a few bytes.
  ** Enlarge the allocation slightly so that this does not cause problems. */
  return pcache1Alloc(sz + 32);
}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
void sqlite3PageFree(void *p){
  pcache1Free(p);







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** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
** exists, this function falls back to sqlite3Malloc().
*/
void *sqlite3PageMalloc(int sz){
  /* During rebalance operations on a corrupt database file, it is sometimes
  ** (rarely) possible to overread the temporary page buffer by a few bytes.
  ** Enlarge the allocation slightly so that this does not cause problems. */
  return pcache1Alloc(sz);
}

/*
** Free an allocated buffer obtained from sqlite3PageMalloc().
*/
void sqlite3PageFree(void *p){
  pcache1Free(p);