From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Reilly Grant <reillyg@chromium.org>
Date: Wed, 22 Jul 2020 04:00:16 +0000
Subject: usb: Prevent iterator invalidation during Promise resolution

This change swaps sets of ScriptPromiseResolvers into local variables in
a number of places where it was possible for script to execute during
the call to Resolve() or Reject() and modify the set being iterated
over, thus invalidating the iterator.

(cherry picked from commit dbc6c3c3652680e287c60b3c6551622748543439)

Bug: 1106773
Change-Id: Id4eb0cd444a7dbb5de23038ec80f44fee649cfe4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2304538
Auto-Submit: Reilly Grant <reillyg@chromium.org>
Commit-Queue: James Hollyer <jameshollyer@chromium.org>
Reviewed-by: James Hollyer <jameshollyer@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#790217}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310964
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/branch-heads/4183@{#842}
Cr-Branched-From: 740e9e8a40505392ba5c8e022a8024b3d018ca65-refs/heads/master@{#782793}

diff --git a/third_party/blink/renderer/modules/webusb/usb.cc b/third_party/blink/renderer/modules/webusb/usb.cc
index de66613d20851dee9a96a8fdcfaec30da9f05b53..e3dc44eb208946aac4a2f836365127ba88c08edd 100644
--- a/third_party/blink/renderer/modules/webusb/usb.cc
+++ b/third_party/blink/renderer/modules/webusb/usb.cc
@@ -254,15 +254,22 @@ void USB::OnDeviceRemoved(UsbDeviceInfoPtr device_info) {
 void USB::OnServiceConnectionError() {
   service_.reset();
   client_receiver_.reset();
-  for (ScriptPromiseResolver* resolver : get_devices_requests_)
+
+  // Move the set to a local variable to prevent script execution in Resolve()
+  // from invalidating the iterator used by the loop.
+  HeapHashSet<Member<ScriptPromiseResolver>> get_devices_requests;
+  get_devices_requests.swap(get_devices_requests_);
+  for (auto& resolver : get_devices_requests)
     resolver->Resolve(HeapVector<Member<USBDevice>>(0));
-  get_devices_requests_.clear();
 
-  for (ScriptPromiseResolver* resolver : get_permission_requests_) {
+  // Move the set to a local variable to prevent script execution in Reject()
+  // from invalidating the iterator used by the loop.
+  HeapHashSet<Member<ScriptPromiseResolver>> get_permission_requests;
+  get_permission_requests.swap(get_permission_requests_);
+  for (auto& resolver : get_permission_requests) {
     resolver->Reject(MakeGarbageCollected<DOMException>(
         DOMExceptionCode::kNotFoundError, kNoDeviceSelected));
   }
-  get_permission_requests_.clear();
 }
 
 void USB::AddedEventListener(const AtomicString& event_type,
diff --git a/third_party/blink/renderer/modules/webusb/usb_device.cc b/third_party/blink/renderer/modules/webusb/usb_device.cc
index 655212ee5dd6c27498b83b8eb5b9e13a14c38a40..17f52e86a134ceb137923b65d1686ce3cbf3bf85 100644
--- a/third_party/blink/renderer/modules/webusb/usb_device.cc
+++ b/third_party/blink/renderer/modules/webusb/usb_device.cc
@@ -1125,11 +1125,15 @@ void USBDevice::AsyncReset(ScriptPromiseResolver* resolver, bool success) {
 void USBDevice::OnConnectionError() {
   device_.reset();
   opened_ = false;
-  for (ScriptPromiseResolver* resolver : device_requests_) {
+
+  // Move the set to a local variable to prevent script execution in Reject()
+  // from invalidating the iterator used by the loop.
+  HeapHashSet<Member<ScriptPromiseResolver>> device_requests;
+  device_requests.swap(device_requests_);
+  for (auto& resolver : device_requests) {
     resolver->Reject(MakeGarbageCollected<DOMException>(
         DOMExceptionCode::kNotFoundError, kDeviceDisconnected));
   }
-  device_requests_.clear();
 }
 
 bool USBDevice::MarkRequestComplete(ScriptPromiseResolver* resolver) {
