daandemeyer / rpms / systemd

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From 73b87f8c73af714a32e7b56b217cd4e4f46a5ea7 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Wed, 8 May 2019 14:39:57 +0200
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Subject: [PATCH] sd-event: add sd_event_source_disable_unref() helper
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(cherry picked from commit afd15bbb4b6414b9356799c63029e36642dae8e4)
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Related: CVE-2020-1712
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---
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 man/rules/meson.build              |  4 +++-
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 man/sd_event_source_unref.xml      | 30 +++++++++++++++++++-----------
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 src/libsystemd/libsystemd.sym      |  1 +
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 src/libsystemd/sd-event/sd-event.c |  6 ++++++
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 src/systemd/sd-event.h             |  1 +
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 5 files changed, 30 insertions(+), 12 deletions(-)
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diff --git a/man/rules/meson.build b/man/rules/meson.build
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index 989d11c9b9..7ae94ea265 100644
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--- a/man/rules/meson.build
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+++ b/man/rules/meson.build
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@@ -340,7 +340,9 @@ manpages = [
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  ['sd_event_source_set_userdata', '3', ['sd_event_source_get_userdata'], ''],
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  ['sd_event_source_unref',
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   '3',
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-  ['sd_event_source_ref', 'sd_event_source_unrefp'],
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+  ['sd_event_source_disable_unref',
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+   'sd_event_source_ref',
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+   'sd_event_source_unrefp'],
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   ''],
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  ['sd_event_wait',
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   '3',
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diff --git a/man/sd_event_source_unref.xml b/man/sd_event_source_unref.xml
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index d1b83c57aa..af8fed33f2 100644
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--- a/man/sd_event_source_unref.xml
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+++ b/man/sd_event_source_unref.xml
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@@ -22,6 +22,7 @@
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     <refname>sd_event_source_unref</refname>
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     <refname>sd_event_source_unrefp</refname>
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     <refname>sd_event_source_ref</refname>
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+    <refname>sd_event_source_disable_unref</refname>
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     <refpurpose>Increase or decrease event source reference counters</refpurpose>
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   </refnamediv>
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@@ -45,6 +46,10 @@
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         <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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       </funcprototype>
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+      <funcprototype>
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+        <funcdef>sd_event_source* <function>sd_event_source_disable_unref</function></funcdef>
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+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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+      </funcprototype>
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     </funcsynopsis>
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   </refsynopsisdiv>
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@@ -80,23 +85,26 @@
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     the passed event source object is
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     <constant>NULL</constant>.</para>
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-    <para>Note that event source objects stay alive and may be
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-    dispatched as long as they have a reference counter greater than
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-    zero. In order to drop a reference of an event source and make
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-    sure the associated event source handler function is not called
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-    anymore it is recommended to combine a call of
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+    <para>Note that event source objects stay alive and may be dispatched as long as they have a reference
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+    counter greater than zero. In order to drop a reference of an event source and make sure the associated
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+    event source handler function is not called anymore it is recommended to combine a call of
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     <function>sd_event_source_unref()</function> with a prior call to
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-    <function>sd_event_source_set_enabled()</function> with
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-    <constant>SD_EVENT_OFF</constant>.</para>
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+    <function>sd_event_source_set_enabled()</function> with <constant>SD_EVENT_OFF</constant> or call
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+    <function>sd_event_source_disable_unref()</function>, see below.</para>
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+
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+    <para><function>sd_event_source_disable_unref()</function> combines a call to
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+    <function>sd_event_source_set_enabled()</function> with <constant>SD_EVENT_OFF</constant> with
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+    <function>sd_event_source_unref()</function>. This ensures that the source is disabled before the local
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+    reference to it is lost. The <parameter>source</parameter> parameter is allowed to be
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+    <constant>NULL</constant>.</para>
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   </refsect1>
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   <refsect1>
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     <title>Return Value</title>
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-    <para><function>sd_event_source_unref()</function> always returns
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-    <constant>NULL</constant>.
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-    <function>sd_event_source_ref()</function> always returns the
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-    event source object passed in.</para>
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+    <para><function>sd_event_source_unref()</function> and
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+    <function>sd_event_source_disable_unref()</function> always return <constant>NULL</constant>.
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+    <function>sd_event_source_ref()</function> always returns the event source object passed in.</para>
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   </refsect1>
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   <xi:include href="libsystemd-pkgconfig.xml" />
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diff --git a/src/libsystemd/libsystemd.sym b/src/libsystemd/libsystemd.sym
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index e9972593a6..778e88a16c 100644
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--- a/src/libsystemd/libsystemd.sym
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+++ b/src/libsystemd/libsystemd.sym
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@@ -570,4 +570,5 @@ global:
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         sd_event_source_set_destroy_callback;
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         sd_event_source_get_destroy_callback;
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         sd_bus_enqueue_for_read;
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+        sd_event_source_disable_unref;
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 } LIBSYSTEMD_238;
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diff --git a/src/libsystemd/sd-event/sd-event.c b/src/libsystemd/sd-event/sd-event.c
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index d53b9a7026..0d3bf5cbb6 100644
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--- a/src/libsystemd/sd-event/sd-event.c
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+++ b/src/libsystemd/sd-event/sd-event.c
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@@ -580,6 +580,12 @@ _public_ sd_event* sd_event_unref(sd_event *e) {
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         return NULL;
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 }
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+_public_ sd_event_source* sd_event_source_disable_unref(sd_event_source *s) {
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+        if (s)
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+                (void) sd_event_source_set_enabled(s, SD_EVENT_OFF);
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+        return sd_event_source_unref(s);
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+}
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+
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 static bool event_pid_changed(sd_event *e) {
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         assert(e);
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diff --git a/src/systemd/sd-event.h b/src/systemd/sd-event.h
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index 7fcae4ac49..9876be01c6 100644
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--- a/src/systemd/sd-event.h
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+++ b/src/systemd/sd-event.h
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@@ -113,6 +113,7 @@ int sd_event_get_iteration(sd_event *e, uint64_t *ret);
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 sd_event_source* sd_event_source_ref(sd_event_source *s);
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 sd_event_source* sd_event_source_unref(sd_event_source *s);
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+sd_event_source* sd_event_source_disable_unref(sd_event_source *s);
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 sd_event *sd_event_source_get_event(sd_event_source *s);
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 void* sd_event_source_get_userdata(sd_event_source *s);