SERVER-17264: improve bson validation for utf-8 strings

(cherry picked from commit 394a8569ff14a215c0691aa34440227b2e62a4de)

2 files changed, 21 insertions, 0 deletions

diff --git a/src/mongo/bson/bson_validate.cpp b/src/mongo/bson/bson_validate.cpp
index cd11f4bb77a..5e0a0341909 100644
--- a/src/mongo/bson/bson_validate.cpp
+++ b/src/mongo/bson/bson_validate.cpp
@@ -90,6 +90,11 @@ namespace mongo {
                 if ( !readNumber<int>( &sz ) )
                     return makeError("invalid bson", _idElem);
 
+                if ( sz <= 0 ) {
+                    // must have NULL at the very least
+                    return makeError("invalid bson", _idElem);
+                }
+
                 if ( out ) {
                     *out = StringData( _buffer + _position, sz );
                 }
diff --git a/src/mongo/bson/bson_validate_test.cpp b/src/mongo/bson/bson_validate_test.cpp
index c31ad0140df..6dce13d0ff6 100644
--- a/src/mongo/bson/bson_validate_test.cpp
+++ b/src/mongo/bson/bson_validate_test.cpp
@@ -292,4 +292,20 @@ namespace {
         ASSERT_NOT_OK(status);
         ASSERT_EQUALS(status.reason(), "not null terminated string in object with unknown _id");
     }
+
+    TEST(BSONValidateFast, StringHasSomething) {
+        BufBuilder bb;
+        BSONObjBuilder ob(bb);
+        bb.appendChar(String);
+        bb.appendStr("x", /*withNUL*/true);
+        bb.appendNum(0);
+        const BSONObj x = ob.done();
+        ASSERT_EQUALS(5 // overhead
+                      + 1 // type
+                      + 2 // name
+                      + 4 // size
+                      , x.objsize());
+        ASSERT_NOT_OK(validateBSON(x.objdata(), x.objsize()));
+    }
+
 }