Major - P3 ISSUE SUMMARY
When inserting documents, MongoDB validates the values for certain fields for correctness. For example, the _id field cannot be an array. A bug in the insertion code caused this validation to stop after the first encountered timestamp field and would therefore allow documents to be inserted that would normally not pass validation.
USER IMPACT
This can cause invalid documents to be stored in a collection. This in turn can cause problems when the invalid document is later read.
WORKAROUNDS
The issue only arises if users attempt to insert documents with invalid values. However, if users want to rely on this safety check, they can place any timestamp fields at the very end of the document to avoid this issue. Note that some drivers may not preserve the order of fields in a document.
AFFECTED VERSIONS
MongoDB 2.6.0 and 2.6.1 are affected by the issue.
FIX VERSION
The fix is included in the 2.6.2 production release.
RESOLUTION DETAILS
The problem was an erroneous break statement that would prematurely end validation. The break has been removed.
Original description
AD-MAC10G:~ alexander$ mongo
MongoDB shell version: 2.6.0
connecting to: test
> db.test.insert({ts:Timestamp(0,0), _id : [1,2]})
WriteResult({ "nInserted" : 1 })
> db.test.find()
{ "_id" : [ 1, 2 ], "ts" : Timestamp(1398896760, 1) }
> db.test.insert({_id : [1,2]})
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 2,
"errmsg" : "can't use an array for _id"
}
})
That's the problematic "break" :
BSONObjIterator i( doc );
while ( i.more() ) {
BSONElement e = i.next();
if ( e.type() == Timestamp && e.timestampValue() == 0 ) {
// we replace Timestamp(0,0) at the top level with a correct value
// in the fast pass, we just mark that we want to swap
hasTimestampToFix = true;
break;
}