SERVER-22710 Fix UB in ASIO timeout durations

std::chrono types can naturally signed integer overflow if you
accidentally pass a large duration in lower granularity
(std::chrono::milliseconds::max()) to a higher granularity constructor
(std::chrono::nanoseconds).

We have to clamp our casts to ensure that we don't wrap around to
negative values.

3 files changed, 9 insertions, 2 deletions

diff --git a/src/mongo/executor/connection_pool_asio.cpp b/src/mongo/executor/connection_pool_asio.cpp
index b2344b54ffa..82e4264d997 100644
--- a/src/mongo/executor/connection_pool_asio.cpp
+++ b/src/mongo/executor/connection_pool_asio.cpp
@@ -52,12 +52,14 @@ ASIOTimer::~ASIOTimer() {
     ++_callbackSharedState->id;
 }
 
+const auto kMaxTimerDuration = duration_cast<Milliseconds>(ASIOTimer::clock_type::duration::max());
+
 void ASIOTimer::setTimeout(Milliseconds timeout, TimeoutCallback cb) {
     _strand->dispatch([this, timeout, cb] {
         _cb = std::move(cb);
 
         cancelTimeout();
-        _impl.expires_after(timeout);
+        _impl.expires_after(std::min(kMaxTimerDuration, timeout));
 
         decltype(_callbackSharedState->id) id;
         decltype(_callbackSharedState) sharedState;
diff --git a/src/mongo/executor/connection_pool_asio.h b/src/mongo/executor/connection_pool_asio.h
index 20b728e542e..55e0f9d34fc 100644
--- a/src/mongo/executor/connection_pool_asio.h
+++ b/src/mongo/executor/connection_pool_asio.h
@@ -44,6 +44,8 @@ namespace connection_pool_asio {
  */
 class ASIOTimer final : public ConnectionPool::TimerInterface {
 public:
+    using clock_type = asio::steady_timer::clock_type;
+
     ASIOTimer(asio::io_service::strand* strand);
     ~ASIOTimer();
 
diff --git a/src/mongo/executor/network_interface_asio.cpp b/src/mongo/executor/network_interface_asio.cpp
index 2324482279d..7da182d2073 100644
--- a/src/mongo/executor/network_interface_asio.cpp
+++ b/src/mongo/executor/network_interface_asio.cpp
@@ -379,9 +379,12 @@ void NetworkInterfaceASIO::cancelAllCommands() {
     }
 }
 
+const auto kMaxTimerDuration = duration_cast<Milliseconds>(asio::steady_timer::duration::max());
+
 void NetworkInterfaceASIO::setAlarm(Date_t when, const stdx::function<void()>& action) {
     // "alarm" must stay alive until it expires, hence the shared_ptr.
-    auto alarm = std::make_shared<asio::steady_timer>(_io_service, when - now());
+    auto alarm = std::make_shared<asio::steady_timer>(_io_service,
+                                                      std::min(when - now(), kMaxTimerDuration));
     alarm->async_wait([alarm, this, action](std::error_code ec) {
         if (!ec) {
             return action();