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Fix a PolkitAgentSession race condition

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This commit is contained in:
Miloslav Trmač 2014-02-11 11:09:04 +01:00
parent 5d7095ad13
commit f3502e1334
2 changed files with 128 additions and 1 deletions
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120
polkit-0.112-PolkitAgentSession-race.patch Normal file
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@ -0,0 +1,120 @@
From 7650ad1e08ab13bdb461783c4995d186d9392840 Mon Sep 17 00:00:00 2001
From: Rui Matos <tiagomatos@gmail.com>
Date: Thu, 6 Feb 2014 18:41:18 +0100
Subject: [PATCH] PolkitAgentSession: fix race between child and io watches
The helper flushes and fdatasyncs stdout and stderr before terminating
but this doesn't guarantee that our io watch is called before our
child watch. This means that we can end up with a successful return
from the helper which we still report as a failure.
If we add G_IO_HUP and G_IO_ERR to the conditions we look for in the
io watch and the child terminates we still run the io watch handler
which will complete the session.
This means that the child watch is in fact needless and we can remove
it.
https://bugs.freedesktop.org/show_bug.cgi?id=60847
---
src/polkitagent/polkitagentsession.c | 47 +++++++++---------------------------
1 file changed, 11 insertions(+), 36 deletions(-)
diff --git a/src/polkitagent/polkitagentsession.c b/src/polkitagent/polkitagentsession.c
index 1c7a2dc..f014773 100644
--- a/src/polkitagent/polkitagentsession.c
+++ b/src/polkitagent/polkitagentsession.c
@@ -92,7 +92,6 @@ struct _PolkitAgentSession
int child_stdout;
GPid child_pid;
- GSource *child_watch_source;
GSource *child_stdout_watch_source;
GIOChannel *child_stdout_channel;
@@ -377,13 +376,6 @@ kill_helper (PolkitAgentSession *session)
session->child_pid = 0;
}
- if (session->child_watch_source != NULL)
- {
- g_source_destroy (session->child_watch_source);
- g_source_unref (session->child_watch_source);
- session->child_watch_source = NULL;
- }
-
if (session->child_stdout_watch_source != NULL)
{
g_source_destroy (session->child_stdout_watch_source);
@@ -429,26 +421,6 @@ complete_session (PolkitAgentSession *session,
}
}
-static void
-child_watch_func (GPid pid,
- gint status,
- gpointer user_data)
-{
- PolkitAgentSession *session = POLKIT_AGENT_SESSION (user_data);
-
- if (G_UNLIKELY (_show_debug ()))
- {
- g_print ("PolkitAgentSession: in child_watch_func for pid %d (WIFEXITED=%d WEXITSTATUS=%d)\n",
- (gint) pid,
- WIFEXITED(status),
- WEXITSTATUS(status));
- }
-
- /* kill all the watches we have set up, except for the child since it has exited already */
- session->child_pid = 0;
- complete_session (session, FALSE);
-}
-
static gboolean
io_watch_have_data (GIOChannel *channel,
GIOCondition condition,
@@ -475,10 +447,13 @@ io_watch_have_data (GIOChannel *channel,
NULL,
NULL,
&error);
- if (error != NULL)
+ if (error != NULL || line == NULL)
{
- g_warning ("Error reading line from helper: %s", error->message);
- g_error_free (error);
+ /* In case we get just G_IO_HUP, line is NULL but error is
+ unset.*/
+ g_warning ("Error reading line from helper: %s",
+ error ? error->message : "nothing to read");
+ g_clear_error (&error);
complete_session (session, FALSE);
goto out;
@@ -540,6 +515,9 @@ io_watch_have_data (GIOChannel *channel,
g_free (line);
g_free (unescaped);
+ if (condition & (G_IO_ERR | G_IO_HUP))
+ complete_session (session, FALSE);
+
/* keep the IOChannel around */
return TRUE;
}
@@ -650,12 +628,9 @@ polkit_agent_session_initiate (PolkitAgentSession *session)
if (G_UNLIKELY (_show_debug ()))
g_print ("PolkitAgentSession: spawned helper with pid %d\n", (gint) session->child_pid);
- session->child_watch_source = g_child_watch_source_new (session->child_pid);
- g_source_set_callback (session->child_watch_source, (GSourceFunc) child_watch_func, session, NULL);
- g_source_attach (session->child_watch_source, g_main_context_get_thread_default ());
-
session->child_stdout_channel = g_io_channel_unix_new (session->child_stdout);
- session->child_stdout_watch_source = g_io_create_watch (session->child_stdout_channel, G_IO_IN);
+ session->child_stdout_watch_source = g_io_create_watch (session->child_stdout_channel,
+ G_IO_IN | G_IO_ERR | G_IO_HUP);
g_source_set_callback (session->child_stdout_watch_source, (GSourceFunc) io_watch_have_data, session, NULL);
g_source_attach (session->child_stdout_watch_source, g_main_context_get_thread_default ());
--
1.8.3.1

9
polkit.spec
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@ -6,13 +6,15 @@
Summary: An authorization framework
Name: polkit
Version: 0.112
Release: 2%{?dist}
Release: 3%{?dist}
License: LGPLv2+
URL: http://www.freedesktop.org/wiki/Software/polkit
Source0: http://www.freedesktop.org/software/polkit/releases/%{name}-%{version}.tar.gz
Source1: http://www.freedesktop.org/software/polkit/releases/%{name}-%{version}.tar.gz.sign
# https://bugs.freedesktop.org/show_bug.cgi?id=71894
Patch0: polkit-0.112-XDG_RUNTIME_DIR.patch
# https://bugs.freedesktop.org/show_bug.cgi?id=60847
Patch1: polkit-0.112-PolkitAgentSession-race.patch
Group: System Environment/Libraries
BuildRequires: glib2-devel >= 2.30.0
BuildRequires: expat-devel
@ -80,6 +82,7 @@ Development documentation for polkit.
%prep
%setup -q
%patch0 -p1 -b .XDG_RUNTIME_DIR
%patch1 -p1 -b .PolkitAgentSession-race
%build
%if 0%{?enable_autoreconf}
@ -166,6 +169,10 @@ exit 0
%{_datadir}/gtk-doc
%changelog
* Mon Feb 10 2014 Miloslav Trmač <mitr@redhat.com> - 0.112-3
- Fix a PolkitAgentSession race condition
Resolves: #1063193
* Sat Dec 7 2013 Miloslav Trmač <mitr@redhat.com> - 0.112-2
- Workaround pam_systemd setting broken XDG_RUNTIME_DIR
Resolves: #1033774