From 83328dadb7aba72fc9202c91d5715ab4a2d04fcb Mon Sep 17 00:00:00 2001
From: Louis Williams <louis.williams@mongodb.com>
Date: Fri, 26 Oct 2018 12:06:36 -0400
Subject: [PATCH] SERVER-37749 replSetResizeOplog command does not validate
 argument correctly

---
 .../noPassthrough/repl_set_resize_oplog.js    | 47 +++++++++++++++++++
 src/mongo/db/commands/resize_oplog.cpp        | 10 +++-
 2 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 jstests/noPassthrough/repl_set_resize_oplog.js

diff --git a/jstests/noPassthrough/repl_set_resize_oplog.js b/jstests/noPassthrough/repl_set_resize_oplog.js
new file mode 100644
index 00000000000..23682467f9d
--- /dev/null
+++ b/jstests/noPassthrough/repl_set_resize_oplog.js
@@ -0,0 +1,47 @@
+/**
+ * Tests that resizing the oplog works as expected and validates input arguments.
+ *
+ * @tags: [requires_replication, requires_wiredtiger]
+ */
+(function() {
+    "use strict";
+
+    let replSet = new ReplSetTest({nodes: 2, oplogSize: 50});
+    replSet.startSet();
+    replSet.initiate();
+
+    let primary = replSet.getPrimary();
+
+    const MB = 1024 * 1024;
+    const GB = 1024 * MB;
+    const PB = 1024 * GB;
+    const EB = 1024 * PB;
+
+    assert.eq(primary.getDB('local').oplog.rs.stats().maxSize, 50 * MB);
+
+    // Too small: 990MB
+    assert.commandFailedWithCode(
+        primary.getDB('admin').runCommand({replSetResizeOplog: 1, size: 900}),
+        ErrorCodes.InvalidOptions,
+        "Expected replSetResizeOplog to fail because the size was too small");
+
+    // Way too small: -1GB
+    assert.commandFailedWithCode(
+        primary.getDB('admin').runCommand({replSetResizeOplog: 1, size: -1 * GB / MB}),
+        ErrorCodes.InvalidOptions,
+        "Expected replSetResizeOplog to fail because the size was too small");
+
+    // Too big: 8EB
+    assert.commandFailedWithCode(
+        primary.getDB('admin').runCommand({replSetResizeOplog: 1, size: 8 * EB / MB}),
+        ErrorCodes.InvalidOptions,
+        "Expected replSetResizeOplog to fail because the size was too big");
+
+    // The maximum: 1PB
+    assert.commandWorked(
+        primary.getDB('admin').runCommand({replSetResizeOplog: 1, size: 1 * PB / MB}));
+
+    assert.eq(primary.getDB('local').oplog.rs.stats().maxSize, 1 * PB);
+
+    replSet.stopSet();
+})();
diff --git a/src/mongo/db/commands/resize_oplog.cpp b/src/mongo/db/commands/resize_oplog.cpp
index 35d230459bc..95abdb5677d 100644
--- a/src/mongo/db/commands/resize_oplog.cpp
+++ b/src/mongo/db/commands/resize_oplog.cpp
@@ -1,4 +1,3 @@
-
 /**
  *    Copyright (C) 2018-present MongoDB, Inc.
  *
@@ -101,10 +100,17 @@ public:
         }
 
         long long sizeMb = jsobj["size"].numberLong();
-        long long size = sizeMb * 1024 * 1024;
         if (sizeMb < 990L) {
             uasserted(ErrorCodes::InvalidOptions, "oplog size should be 990MB at least");
         }
+
+        const long long kMB = 1024 * 1024;
+        const long long kPB = kMB * 1024 * 1024 * 1024;
+        if (sizeMb > kPB / kMB) {
+            uasserted(ErrorCodes::InvalidOptions, "oplog size in MB cannot exceed maximum of 1PB");
+        }
+        long long size = sizeMb * kMB;
+
         WriteUnitOfWork wunit(opCtx);
         Status status = coll->getRecordStore()->updateCappedSize(opCtx, size);
         uassertStatusOK(status);