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Prevent crash on dbus reconnection (#2186468)

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This commit is contained in:
Petr Menšík 2023-04-27 11:46:29 +02:00
parent c4797a90af
commit 9234006b7d
2 changed files with 99 additions and 1 deletions
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93
dnsmasq-2.90-dbus-watchers-bz2186468.patch Normal file
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@ -0,0 +1,93 @@
From 33635d8564f96cedcef9bf9826cbbca76f28aa81 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@redhat.com>
Date: Mon, 17 Apr 2023 20:55:31 +0100
Subject: [PATCH] Fix crash in dbus code.
If I configure dnsmasq to use dbus and then restart dbus.service with watchers present,
it crashes dnsmasq. The reason is simple, it uses loop to walk over watchers to call
dbus handling code. But from that code the same list can be modified and watchers removed.
But the list iteration continues anyway.
Restart the loop if list were modified.
---
src/dbus.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/src/dbus.c b/src/dbus.c
index 24efcb8..34cf2f6 100644
--- a/src/dbus.c
+++ b/src/dbus.c
@@ -106,6 +106,7 @@ const char* introspection_xml_template =
"</node>\n";
static char *introspection_xml = NULL;
+static int watches_modified = 0;
struct watch {
DBusWatch *watch;
@@ -127,6 +128,7 @@ static dbus_bool_t add_watch(DBusWatch *watch, void *data)
w->watch = watch;
w->next = daemon->watches;
daemon->watches = w;
+ watches_modified++;
(void)data; /* no warning */
return TRUE;
@@ -134,7 +136,7 @@ static dbus_bool_t add_watch(DBusWatch *watch, void *data)
static void remove_watch(DBusWatch *watch, void *data)
{
- struct watch **up, *w, *tmp;
+ struct watch **up, *w, *tmp;
for (up = &(daemon->watches), w = daemon->watches; w; w = tmp)
{
@@ -143,6 +145,7 @@ static void remove_watch(DBusWatch *watch, void *data)
{
*up = tmp;
free(w);
+ watches_modified++;
}
else
up = &(w->next);
@@ -966,11 +969,11 @@ void set_dbus_listeners(void)
}
}
-void check_dbus_listeners()
+static int check_dbus_watches()
{
- DBusConnection *connection = (DBusConnection *)daemon->dbus;
struct watch *w;
+ watches_modified = 0;
for (w = daemon->watches; w; w = w->next)
if (dbus_watch_get_enabled(w->watch))
{
@@ -987,9 +990,22 @@ void check_dbus_listeners()
flags |= DBUS_WATCH_ERROR;
if (flags != 0)
- dbus_watch_handle(w->watch, flags);
+ {
+ dbus_watch_handle(w->watch, flags);
+ if (watches_modified)
+ return 0;
+ }
}
+ return 1;
+}
+
+void check_dbus_listeners()
+{
+ DBusConnection *connection = (DBusConnection *)daemon->dbus;
+
+ while (!check_dbus_watches()) ;
+
if (connection)
{
dbus_connection_ref (connection);
--
2.40.0

7
dnsmasq.spec
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@ -23,7 +23,7 @@
Name: dnsmasq
Version: 2.89
Release: 4%{?extraversion:.%{extraversion}}%{?dist}
Release: 5%{?extraversion:.%{extraversion}}%{?dist}
Summary: A lightweight DHCP/caching DNS server
# SPDX identifiers already
@ -47,6 +47,8 @@ Patch2: dnsmasq-2.81-configuration.patch
Patch3: dnsmasq-2.78-fips.patch
# https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;h=eb92fb32b746f2104b0f370b5b295bb8dd4bd5e5
Patch4: dnsmasq-2.89-edns0-size.patch
# http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=33635d8564f96cedcef9bf9826cbbca76f28aa81
Patch5: dnsmasq-2.90-dbus-watchers-bz2186468.patch
Requires: nettle
@ -217,6 +219,9 @@ install -Dpm 644 %{SOURCE2} %{buildroot}%{_sysusersdir}/%{name}.conf
%endif
%changelog
* Thu Apr 27 2023 Petr Menšík <pemensik@redhat.com> - 2.89-5
- Prevent crash on dbus reconnection (#2186468)
* Thu Apr 27 2023 Petr Menšík <pemensik@redhat.com> - 2.89-4
- Actually enable localization support in dnsmasq (#2131681)