SERVER-42657 Make DataType<BSONObj> noexcept safer4.2.0-rc8

(cherry picked from commit d7455e67f5b002de110f7972603906888aff66b8)

3 files changed, 40 insertions, 4 deletions

diff --git a/src/mongo/bson/bsonobj.cpp b/src/mongo/bson/bsonobj.cpp
index 7b5439cd40a..a0628fa9c3c 100644
--- a/src/mongo/bson/bsonobj.cpp
+++ b/src/mongo/bson/bsonobj.cpp
@@ -618,8 +618,11 @@ void BSONObj::toString(
     s << (isArray ? " ]" : " }");
 }
 
-Status DataType::Handler<BSONObj>::store(
-    const BSONObj& bson, char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
+Status DataType::Handler<BSONObj>::store(const BSONObj& bson,
+                                         char* ptr,
+                                         size_t length,
+                                         size_t* advanced,
+                                         std::ptrdiff_t debug_offset) noexcept try {
     if (bson.objsize() > static_cast<int>(length)) {
         str::stream ss;
         ss << "buffer too small to write bson of size (" << bson.objsize()
@@ -636,6 +639,8 @@ Status DataType::Handler<BSONObj>::store(
     }
 
     return Status::OK();
+} catch (const DBException& e) {
+    return e.toStatus();
 }
 
 std::ostream& operator<<(std::ostream& s, const BSONObj& o) {
diff --git a/src/mongo/bson/bsonobj.h b/src/mongo/bson/bsonobj.h
index 86f858258ad..5f50271e4c7 100644
--- a/src/mongo/bson/bsonobj.h
+++ b/src/mongo/bson/bsonobj.h
@@ -826,7 +826,7 @@ struct DataType::Handler<BSONObj> {
                        const char* ptr,
                        size_t length,
                        size_t* advanced,
-                       std::ptrdiff_t debug_offset) {
+                       std::ptrdiff_t debug_offset) noexcept try {
         auto temp = BSONObj(ptr);
         auto len = temp.objsize();
         if (bson) {
@@ -836,13 +836,15 @@ struct DataType::Handler<BSONObj> {
             *advanced = len;
         }
         return Status::OK();
+    } catch (const DBException& e) {
+        return e.toStatus();
     }
 
     static Status store(const BSONObj& bson,
                         char* ptr,
                         size_t length,
                         size_t* advanced,
-                        std::ptrdiff_t debug_offset);
+                        std::ptrdiff_t debug_offset) noexcept;
 
     static BSONObj defaultConstruct() {
         return BSONObj();
diff --git a/src/mongo/rpc/op_msg_integration_test.cpp b/src/mongo/rpc/op_msg_integration_test.cpp
index 7aa41d66cb1..8ee613a3616 100644
--- a/src/mongo/rpc/op_msg_integration_test.cpp
+++ b/src/mongo/rpc/op_msg_integration_test.cpp
@@ -468,4 +468,33 @@ TEST(OpMsg, ServerRepliesWithoutChecksumToRequestWithoutChecksum) {
 TEST(OpMsg, ServerRepliesWithChecksumToRequestWithChecksum) {
     checksumTest(true);
 }
+
+TEST(OpMsg, ServerHandlesReallyLargeMessagesGracefully) {
+    std::string errMsg;
+    auto conn = unittest::getFixtureConnectionString().connect("integration_test", errMsg);
+    uassert(ErrorCodes::SocketException, errMsg, conn);
+
+    auto buildInfo = conn->runCommand(OpMsgRequest::fromDBAndBody("admin", BSON("buildInfo" << 1)))
+                         ->getCommandReply();
+    ASSERT_OK(getStatusFromCommandResult(buildInfo));
+    const auto maxBSONObjSizeFromServer =
+        static_cast<size_t>(buildInfo["maxBsonObjectSize"].Number());
+    const std::string bigData(maxBSONObjSizeFromServer * 2, ' ');
+
+    BSONObjBuilder bob;
+    bob << "ismaster" << 1 << "ignoredField" << bigData << "$db"
+        << "admin";
+    OpMsgRequest request;
+    request.body = bob.obj<BSONObj::LargeSizeTrait>();
+    ASSERT_GT(request.body.objsize(), BSONObjMaxInternalSize);
+    auto requestMsg = request.serialize();
+
+    Message replyMsg;
+    ASSERT(conn->call(requestMsg, replyMsg));
+
+    auto reply = OpMsg::parse(replyMsg);
+    auto replyStatus = getStatusFromCommandResult(reply.body);
+    ASSERT_NOT_OK(replyStatus);
+    ASSERT_EQ(replyStatus, ErrorCodes::BSONObjectTooLarge);
+}
 }  // namespace mongo