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Comment:Limit the size of SrcList objects to 200 entries (compile-time configurable using -DSQLITE_MAX_SRCLIST=n). The maximum number of tables in a join has always been 64, so this is not a real constraint on capability. Limiting the size of a SrcList prevents DOS attacks (discovered by OSSFuzz) using crazy nexted CTE joins.
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SHA3-256:7cac614d5df55eb092b863163483b6782b942b21bd15fd787576fef5619fa849
User & Date: drh 2019-01-17 14:34:46
Context
2019-01-17
15:40
Revamp the SrcList allocator routines to be methods of Parse instead of being methods of the "sqlite3" object, so that they can leave better error messages when the SrcList object grows too large. check-in: df08d472 user: drh tags: trunk
14:34
Limit the size of SrcList objects to 200 entries (compile-time configurable using -DSQLITE_MAX_SRCLIST=n). The maximum number of tables in a join has always been 64, so this is not a real constraint on capability. Limiting the size of a SrcList prevents DOS attacks (discovered by OSSFuzz) using crazy nexted CTE joins. check-in: 7cac614d user: drh tags: trunk
04:40
Fix a corner-case for the logic that cause an insert of a NULL into an INTEGER PRIMARY KEY column to be converted into a valid integer key, when the NULL results from a CASE expression that lacks an ELSE clause. check-in: 9a425051 user: drh tags: trunk
Changes
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Changes to src/build.c.

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  if( pList==0 ) return -1;
  for(i=0; i<pList->nId; i++){
    if( sqlite3StrICmp(pList->a[i].zName, zName)==0 ) return i;
  }
  return -1;
}













/*
** Expand the space allocated for the given SrcList object by
** creating nExtra new slots beginning at iStart.  iStart is zero based.
** New slots are zeroed.
**
** For example, suppose a SrcList initially contains two entries: A,B.
** To append 3 new entries onto the end, do this:
................................................................................
  assert( iStart<=pSrc->nSrc );

  /* Allocate additional space if needed */
  if( (u32)pSrc->nSrc+nExtra>pSrc->nAlloc ){
    SrcList *pNew;
    int nAlloc = pSrc->nSrc*2+nExtra;
    int nGot;











    pNew = sqlite3DbRealloc(db, pSrc,
               sizeof(*pSrc) + (nAlloc-1)*sizeof(pSrc->a[0]) );
    if( pNew==0 ){
      assert( db->mallocFailed );
      return pSrc;
    }
    pSrc = pNew;







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  if( pList==0 ) return -1;
  for(i=0; i<pList->nId; i++){
    if( sqlite3StrICmp(pList->a[i].zName, zName)==0 ) return i;
  }
  return -1;
}

/*
** Maximum size of a SrcList object.
** The SrcList object is used to represent the FROM clause of a
** SELECT statement, and the query planner cannot deal with more
** than 64 tables in a join.  So any value larger than 64 here
** is sufficient for most uses.  Smaller values, like say 10, are
** appropriate for small and memory-limited applications.
*/
#ifndef SQLITE_MAX_SRCLIST
# define SQLITE_MAX_SRCLIST 200
#endif

/*
** Expand the space allocated for the given SrcList object by
** creating nExtra new slots beginning at iStart.  iStart is zero based.
** New slots are zeroed.
**
** For example, suppose a SrcList initially contains two entries: A,B.
** To append 3 new entries onto the end, do this:
................................................................................
  assert( iStart<=pSrc->nSrc );

  /* Allocate additional space if needed */
  if( (u32)pSrc->nSrc+nExtra>pSrc->nAlloc ){
    SrcList *pNew;
    int nAlloc = pSrc->nSrc*2+nExtra;
    int nGot;

    if( pSrc->nSrc+nExtra>=SQLITE_MAX_SRCLIST ){
      /* FIXME: Return a better error than SQLITE_NOMEM when the size
      ** of a SrcList object gets to be too big.  To fix this will require
      ** replumbing to pass Parse* instead of sqlite3* as the first parameter
      ** to the SrcList allocators.  As this never comes up in real-world
      ** usage, the fix is a low priority. */
      sqlite3OomFault(db);
      return pSrc;
    }
    if( nAlloc>SQLITE_MAX_SRCLIST ) nAlloc = SQLITE_MAX_SRCLIST;
    pNew = sqlite3DbRealloc(db, pSrc,
               sizeof(*pSrc) + (nAlloc-1)*sizeof(pSrc->a[0]) );
    if( pNew==0 ){
      assert( db->mallocFailed );
      return pSrc;
    }
    pSrc = pNew;

Changes to test/join.test.

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jointest join-12.2 30 {0 1}
jointest join-12.3 63 {0 1}
jointest join-12.4 64 {0 1}
jointest join-12.5 65 {1 {at most 64 tables in a join}}
jointest join-12.6 66 {1 {at most 64 tables in a join}}
jointest join-12.7 127 {1 {at most 64 tables in a join}}
jointest join-12.8 128 {1 {at most 64 tables in a join}}





jointest join-12.9 1000 {1 {at most 64 tables in a join}}

# If SQLite is built with SQLITE_MEMDEBUG, then the huge number of realloc()
# calls made by the following test cases are too time consuming to run.
# Without SQLITE_MEMDEBUG, realloc() is fast enough that these are not
# a problem.

ifcapable pragma&&compileoption_diags {
  if {[lsearch [db eval {PRAGMA compile_options}] MEMDEBUG]<0} {
    jointest join-12.10 65534 {1 {at most 64 tables in a join}}
    jointest join-12.11 65535 {1 {too many references to "t14": max 65535}}
    jointest join-12.12 65536 {1 {too many references to "t14": max 65535}}
    jointest join-12.13 65537 {1 {too many references to "t14": max 65535}}
  }
}




#-------------------------------------------------------------------------
# Test a problem with reordering tables following a LEFT JOIN.
#
do_execsql_test join-13.0 {
  CREATE TABLE aa(a);







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jointest join-12.2 30 {0 1}
jointest join-12.3 63 {0 1}
jointest join-12.4 64 {0 1}
jointest join-12.5 65 {1 {at most 64 tables in a join}}
jointest join-12.6 66 {1 {at most 64 tables in a join}}
jointest join-12.7 127 {1 {at most 64 tables in a join}}
jointest join-12.8 128 {1 {at most 64 tables in a join}}

# As of 2019-01-17, the number of elements in a SrcList is limited
# to 200.  The following tests still run, but the answer is now
# an SQLITE_NOMEM error.
#
# jointest join-12.9 1000 {1 {at most 64 tables in a join}}
#
#  If SQLite is built with SQLITE_MEMDEBUG, then the huge number of realloc()
#  calls made by the following test cases are too time consuming to run.
#  Without SQLITE_MEMDEBUG, realloc() is fast enough that these are not
#  a problem.
#
# ifcapable pragma&&compileoption_diags {
#    if {[lsearch [db eval {PRAGMA compile_options}] MEMDEBUG]<0} {
#     jointest join-12.10 65534 {1 {at most 64 tables in a join}}
#     jointest join-12.11 65535 {1 {too many references to "t14": max 65535}}
#     jointest join-12.12 65536 {1 {too many references to "t14": max 65535}}
#     jointest join-12.13 65537 {1 {too many references to "t14": max 65535}}


#   }
# }


#-------------------------------------------------------------------------
# Test a problem with reordering tables following a LEFT JOIN.
#
do_execsql_test join-13.0 {
  CREATE TABLE aa(a);

Changes to test/with1.test.

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do_execsql_test 21.2 {
  SELECT printf('',
     EXISTS (WITH RECURSIVE Table0 AS (WITH Table0 AS (SELECT DISTINCT 1)
                                       SELECT *, * FROM Table0 ORDER BY 1 DESC)
             SELECT * FROM Table0  NATURAL JOIN  Table0));
} {{}}





















finish_test







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do_execsql_test 21.2 {
  SELECT printf('',
     EXISTS (WITH RECURSIVE Table0 AS (WITH Table0 AS (SELECT DISTINCT 1)
                                       SELECT *, * FROM Table0 ORDER BY 1 DESC)
             SELECT * FROM Table0  NATURAL JOIN  Table0));
} {{}}

# 2019-01-17
# Make sure crazy nexted CTE joins terminate with an error quickly.
#
do_catchsql_test 22.1 {
  WITH RECURSIVE c AS (
     WITH RECURSIVE c AS (
        WITH RECURSIVE c AS (
           WITH RECURSIVE c AS (
               WITH  c AS (VALUES(0))
               SELECT 1 FROM c LEFT JOIN c ON ltrim(1)
           )
           SELECT 1 FROM c,c,c,c,c,c,c,c,c
        )
        SELECT  2 FROM c,c,c,c,c,c,c,c,c
     )
     SELECT 3 FROM c,c,c,c,c,c,c,c,c
  )
  SELECT 4 FROM c,c,c,c,c,c,c,c,c;
} {1 {out of memory}}

finish_test