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Backport fix for race in name watching (RH #1483205)

This commit is contained in:
Debarshi Ray 2017-11-01 17:37:41 +01:00
parent 3a83a7f74d
commit fc1fb47dc2
2 changed files with 141 additions and 1 deletions
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133
glib2-fix-race-in-name-watching.patch Normal file
View File

@ -0,0 +1,133 @@
From b849ebb5d199da3694e6b6261a931436214f7a0e Mon Sep 17 00:00:00 2001
From: Philip Withnall <withnall@endlessm.com>
Date: Mon, 6 Feb 2017 09:41:10 +0100
Subject: [PATCH] gdbus: Fix race in name watching on connection teardown
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
If g_dbus_unwatch_name() is called from one thread at the same time as
the GDBusConnection is emitting ::disconnected in another thread, there
will be a race and the handler for ::disconnected may end up using
memory after it’s freed.
Fix this by serialising through the map_id_to_client, so that
on_connection_disconnected() atomically gets a strong reference to the
Client, or NULL.
https://bugzilla.gnome.org/show_bug.cgi?id=777307
---
gio/gdbusnamewatching.c | 48 +++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 5 deletions(-)
diff --git a/gio/gdbusnamewatching.c b/gio/gdbusnamewatching.c
index 3cb2b57b7b0f..148fb41cf025 100644
--- a/gio/gdbusnamewatching.c
+++ b/gio/gdbusnamewatching.c
@@ -249,13 +249,43 @@ call_vanished_handler (Client *client,
/* ---------------------------------------------------------------------------------------------------- */
+/* Return a reference to the #Client for @watcher_id, or %NULL if it’s been
+ * unwatched. This is safe to call from any thread. */
+static Client *
+dup_client (guint watcher_id)
+{
+ Client *client;
+
+ G_LOCK (lock);
+
+ g_assert (watcher_id != 0);
+ g_assert (map_id_to_client != NULL);
+
+ client = g_hash_table_lookup (map_id_to_client, GUINT_TO_POINTER (watcher_id));
+
+ if (client != NULL)
+ client_ref (client);
+
+ G_UNLOCK (lock);
+
+ return client;
+}
+
+/* Could be called from any thread, so it could be called after client_unref()
+ * has started finalising the #Client. Avoid that by looking up the #Client
+ * atomically. */
static void
on_connection_disconnected (GDBusConnection *connection,
gboolean remote_peer_vanished,
GError *error,
gpointer user_data)
{
- Client *client = user_data;
+ guint watcher_id = GPOINTER_TO_UINT (user_data);
+ Client *client = NULL;
+
+ client = dup_client (watcher_id);
+ if (client == NULL)
+ return;
if (client->name_owner_changed_subscription_id > 0)
g_dbus_connection_signal_unsubscribe (client->connection, client->name_owner_changed_subscription_id);
@@ -267,10 +297,13 @@ on_connection_disconnected (GDBusConnection *connection,
client->connection = NULL;
call_vanished_handler (client, FALSE);
+
+ client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
+/* Will always be called from the thread which acquired client->main_context. */
static void
on_name_owner_changed (GDBusConnection *connection,
const gchar *sender_name,
@@ -280,11 +313,16 @@ on_name_owner_changed (GDBusConnection *connection,
GVariant *parameters,
gpointer user_data)
{
- Client *client = user_data;
+ guint watcher_id = GPOINTER_TO_UINT (user_data);
+ Client *client = NULL;
const gchar *name;
const gchar *old_owner;
const gchar *new_owner;
+ client = dup_client (watcher_id);
+ if (client == NULL)
+ return;
+
if (!client->initialized)
goto out;
@@ -319,7 +357,7 @@ on_name_owner_changed (GDBusConnection *connection,
}
out:
- ;
+ client_unref (client);
}
/* ---------------------------------------------------------------------------------------------------- */
@@ -444,7 +482,7 @@ has_connection (Client *client)
client->disconnected_signal_handler_id = g_signal_connect (client->connection,
"closed",
G_CALLBACK (on_connection_disconnected),
- client);
+ GUINT_TO_POINTER (client->id));
/* start listening to NameOwnerChanged messages immediately */
client->name_owner_changed_subscription_id = g_dbus_connection_signal_subscribe (client->connection,
@@ -455,7 +493,7 @@ has_connection (Client *client)
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_owner_changed,
- client,
+ GUINT_TO_POINTER (client->id),
NULL);
if (client->flags & G_BUS_NAME_WATCHER_FLAGS_AUTO_START)
--
2.14.3

9
glib2.spec
View File

@ -5,13 +5,16 @@
Name: glib2
Version: 2.52.3
Release: 1%{?dist}
Release: 2%{?dist}
Summary: A library of handy utility functions
License: LGPLv2+
URL: http://www.gtk.org
Source0: http://download.gnome.org/sources/glib/2.52/glib-%{version}.tar.xz
# https://bugzilla.redhat.com/show_bug.cgi?id=1483205
Patch0: glib2-fix-race-in-name-watching.patch
BuildRequires: chrpath
BuildRequires: gettext
BuildRequires: perl-generators
@ -81,6 +84,7 @@ the functionality of the installed glib2 package.
%prep
%setup -q -n glib-%{version}
%patch0 -p1 -b .race-in-name-watching
%build
# Bug 1324770: Also explicitly remove PCRE sources since we use --with-pcre=system
@ -229,6 +233,9 @@ glib-compile-schemas %{_datadir}/glib-2.0/schemas &> /dev/null || :
%{_datadir}/installed-tests
%changelog
* Wed Nov 01 2017 Milan Crha <mcrha@redhat.com> - 2.52.3-2
- Backport fix for race in name watching (RH #1483205)
* Thu Jun 22 2017 Kalev Lember <klember@redhat.com> - 2.52.3-1
- Update to 2.52.3