From 926b1bee1828f6a01d93a3926b756e096c5042d2 Mon Sep 17 00:00:00 2001
From: Nicolas Grekas <nicolas.grekas@gmail.com>
Date: Tue, 30 Jan 2018 16:11:54 +0100
Subject: [PATCH] [Debug] Fix bad registration of exception handler, leading to
 mem leak

---
 src/Symfony/Component/Debug/ErrorHandler.php        | 13 ++++++++++++-
 .../Component/Debug/Tests/ErrorHandlerTest.php      |  2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/Symfony/Component/Debug/ErrorHandler.php b/src/Symfony/Component/Debug/ErrorHandler.php
index 6a15f7b368..8875e03e84 100644
--- a/src/Symfony/Component/Debug/ErrorHandler.php
+++ b/src/Symfony/Component/Debug/ErrorHandler.php
@@ -149,9 +149,20 @@ class ErrorHandler
         }
         if (!$replace && $prev) {
             restore_error_handler();
+            $handlerIsRegistered = is_array($prev) && $handler === $prev[0];
+        } else {
+            $handlerIsRegistered = true;
         }
-        if (is_array($prev = set_exception_handler(array($handler, 'handleException'))) && $prev[0] === $handler) {
+        if (is_array($prev = set_exception_handler(array($handler, 'handleException'))) && $prev[0] instanceof self) {
             restore_exception_handler();
+            if (!$handlerIsRegistered) {
+                $handler = $prev[0];
+            } elseif ($handler !== $prev[0] && $replace) {
+                set_exception_handler(array($handler, 'handleException'));
+                $p = $prev[0]->setExceptionHandler(null);
+                $handler->setExceptionHandler($p);
+                $prev[0]->setExceptionHandler($p);
+            }
         } else {
             $handler->setExceptionHandler($prev);
         }
diff --git a/src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php b/src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php
index 264dc701e7..f2d0fc8b0b 100644
--- a/src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php
+++ b/src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php
@@ -34,7 +34,7 @@ class ErrorHandlerTest extends TestCase
 
             $newHandler = new ErrorHandler();
 
-            $this->assertSame($newHandler, ErrorHandler::register($newHandler, false));
+            $this->assertSame($handler, ErrorHandler::register($newHandler, false));
             $h = set_error_handler('var_dump');
             restore_error_handler();
             $this->assertSame(array($handler, 'handleError'), $h);