SERVER-37749 replSetResizeOplog command does not validate argument correctly

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();
+})();

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);