From 67b99a7fa2aea64c6125fbd501df4e76402415a5 Mon Sep 17 00:00:00 2001
Message-Id: <67b99a7fa2aea64c6125fbd501df4e76402415a5.1390394206.git.jdenemar@redhat.com>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Thu, 9 Jan 2014 22:26:40 +0100
Subject: [PATCH] Don't crash if a connection closes early

CVE-2014-1447

When a client closes its connection to libvirtd early during
virConnectOpen, more specifically just after making
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call to check if
VIR_DRV_FEATURE_PROGRAM_KEEPALIVE is supported without even waiting for
the result, libvirtd may crash due to a race in keep-alive
initialization. Once receiving the REMOTE_PROC_CONNECT_SUPPORTS_FEATURE
call, the daemon's event loop delegates it to a worker thread. In case
the event loop detects EOF on the connection and calls
virNetServerClientClose before the worker thread starts to handle
REMOTE_PROC_CONNECT_SUPPORTS_FEATURE call, client->keepalive will be
disposed by the time virNetServerClientStartKeepAlive gets called from
remoteDispatchConnectSupportsFeature. Because the flow is common for
both authenticated and read-only connections, even unprivileged clients
may cause the daemon to crash.

To avoid the crash, virNetServerClientStartKeepAlive needs to check if
the connection is still open before starting keep-alive protocol.

Every libvirt release since 0.9.8 is affected by this bug.

(cherry picked from commit 173c2914734eb5c32df6d35a82bf503e12261bcf)
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/rpc/virnetserverclient.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/rpc/virnetserverclient.c b/src/rpc/virnetserverclient.c
index 0b9ab52..64e91d3 100644
--- a/src/rpc/virnetserverclient.c
+++ b/src/rpc/virnetserverclient.c
@@ -1533,9 +1533,22 @@ cleanup:
 int
 virNetServerClientStartKeepAlive(virNetServerClientPtr client)
 {
-    int ret;
+    int ret = -1;
+
     virObjectLock(client);
+
+    /* The connection might have been closed before we got here and thus the
+     * keepalive object could have been removed too.
+     */
+    if (!client->sock) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("connection not open"));
+        goto cleanup;
+    }
+
     ret = virKeepAliveStart(client->keepalive, 0, 0);
+
+cleanup:
     virObjectUnlock(client);
     return ret;
 }
-- 
1.8.5.3