backport_1090543.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Cheng Zhao <zcbenz@gmail.com>
Date: Thu, 4 Oct 2018 14:57:02 -0700
Subject: fix: guard against UaF in NavigationRequest

[1090543] [High]: heap-use-after-free : content::NavigationRequest::OnWillProcessResponseProcessed
Backport https://chromium.googlesource.com/chromium/src/+/8a7c8c1affd3b03a41c6f79afa8ebce4168ded5b

diff --git a/content/browser/frame_host/navigation_request.cc b/content/browser/frame_host/navigation_request.cc
index bba7dc934cd43df41949ed5b2adc70e152b77627..d5290c54ed88e3dd2cd736535d5954316ee663a8 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -3012,11 +3012,19 @@ void NavigationRequest::OnWillProcessResponseProcessed(
   DCHECK(processing_navigation_throttle_);
   processing_navigation_throttle_ = false;
   if (result.action() == NavigationThrottle::PROCEED) {
+    base::WeakPtr<NavigationRequest> weak_self(weak_factory_.GetWeakPtr());
+
     // If the navigation is done processing the response, then it's ready to
     // commit. Inform observers that the navigation is now ready to commit,
     // unless it is not set to commit (204/205s/downloads).
     if (render_frame_host_)
       ReadyToCommitNavigation(false);
+
+    // The call above might block on showing a user dialog. The interaction of
+    // the user with this dialog might result in the WebContents owning this
+    // NavigationRequest to be destroyed. Return if this is the case.
+    if (!weak_self)
+      return;
   } else {
     state_ = CANCELING;
   }