commit 98f3df12d48daf277f2e3f056600c64294c628c1 Author: Kathy Brade brade@pearlcrescent.com Date: Wed May 13 10:45:01 2020 -0400

Bug 34164: Tor Launcher deadlocks during startup (Firefox 77)

Initialize the DNS service as early as possible to avoid a problem where DNS service initialization is dispatched to the main thread while that thread is blocked. --- src/components/tl-process.js | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)

diff --git a/src/components/tl-process.js b/src/components/tl-process.js index 31f6801..e9d7cde 100644 --- a/src/components/tl-process.js +++ b/src/components/tl-process.js @@ -100,6 +100,22 @@ TorProcessService.prototype =

if ("profile-after-change" == aTopic) { + // Initialize the DNS service here (as early as possible). This + // avoids a deadlock that can occur inside TorProtocolService's + // _openAuthenticatedConnection() function. What happens in the + // deadlock case is that a Necko socket thread tries to dispatch + // initialization of the DNS service to the main thread while the + // main thread is blocked in a writeBytes() call inside the + // _sendCommand() function. The ultimate solution is to change + // our control port socket to use asynchronous I/O. + // References: + // netwerk/dns/nsDNSService2.cpp nsDNSService::GetSingleton() + // https://bugzilla.mozilla.org/show_bug.cgi?id=1625151 (the + // fix for this bug introduced the deadlock because it changed + // DNS service initialization to occur on the main thread). + const dns = Cc["@mozilla.org/network/dns-service;1"] + .getService(Ci.nsIDNSService); + this.mObsSvc.addObserver(this, "quit-application-granted", false); this.mObsSvc.addObserver(this, kOpenNetworkSettingsTopic, false); this.mObsSvc.addObserver(this, kUserQuitTopic, false);