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Comment:Make sure signed integer overflow does not cause a segfault while attempting to read a corrupt database where the header size varint on a record is larger than the maximum 32-bit signed integer.
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SHA1:c3baca99f4580652afb2c3f73036ab83796a1557
User & Date: drh 2013-08-01 19:17:39
Context
2013-08-01
20:26
Fix a potential buffer overread in sqlite3VdbeRecordCompare() when a serial_type specifies a field that starts in bounds but is much too large for the allocated buffer. Mostly harmless. The overread is unlikely to go more than one or two bytes past the end of the buffer. check-in: e436b2f4 user: drh tags: trunk
19:17
Make sure signed integer overflow does not cause a segfault while attempting to read a corrupt database where the header size varint on a record is larger than the maximum 32-bit signed integer. check-in: c3baca99 user: drh tags: trunk
17:43
Add test case for the problem fixed by [127a5b776d]. check-in: 65816718 user: dan tags: trunk
Changes
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Changes to src/vdbeaux.c.

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** equal, then the keys are considered to be equal and
** the parts beyond the common prefix are ignored.
*/
int sqlite3VdbeRecordCompare(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  int d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
  int nField;
  int rc = 0;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  KeyInfo *pKeyInfo;
................................................................................
  nField = pKeyInfo->nField;
  assert( pKeyInfo->aSortOrder!=0 );
  while( idx1<szHdr1 && i<pPKey2->nField ){
    u32 serial_type1;

    /* Read the serial types for the next element in each key. */
    idx1 += getVarint32( aKey1+idx1, serial_type1 );
    if( d1>=nKey1 && sqlite3VdbeSerialTypeLen(serial_type1)>0 ) break;

    /* Extract the values to be compared.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);

    /* Do the comparison
    */







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** equal, then the keys are considered to be equal and
** the parts beyond the common prefix are ignored.
*/
int sqlite3VdbeRecordCompare(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  u32 d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
  int nField;
  int rc = 0;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  KeyInfo *pKeyInfo;
................................................................................
  nField = pKeyInfo->nField;
  assert( pKeyInfo->aSortOrder!=0 );
  while( idx1<szHdr1 && i<pPKey2->nField ){
    u32 serial_type1;

    /* Read the serial types for the next element in each key. */
    idx1 += getVarint32( aKey1+idx1, serial_type1 );
    if( d1>=(u32)nKey1 && sqlite3VdbeSerialTypeLen(serial_type1)>0 ) break;

    /* Extract the values to be compared.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);

    /* Do the comparison
    */

Added test/corruptG.test.

















































































































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# 2013-08-01
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix corruptG

# Do not use a codec for tests in this file, as the database file is
# manipulated directly using tcl scripts (using the [hexio_write] command).
#
do_not_use_codec

# Create a simple database with a single entry.  Then corrupt the
# header-size varint on the index payload so that it maps into a
# negative number.  Try to use the database.
#

do_execsql_test 1.1 {
  PRAGMA page_size=512;
  CREATE TABLE t1(a,b,c);
  INSERT INTO t1(rowid,a,b,c) VALUES(2,'abc','xyz','123');
  CREATE INDEX t1abc ON t1(a,b,c);
}

# Corrupt the file
db close
hexio_write test.db [expr {3*512 - 15}] 888080807f
sqlite3 db test.db

# Try to use the file.
do_test 1.2 {
  catchsql {
    SELECT c FROM t1 WHERE a>'abc';
  }
} {0 {}}
do_test 1.3 {
  catchsql {
     PRAGMA integrity_check
  }
} {0 ok}
do_test 1.4 {
  catchsql {
    SELECT c FROM t1 ORDER BY a;
  }
} {1 {database disk image is malformed}}

finish_test