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Don't crash if a connection closes early

Browse Source 
https://bugzilla.redhat.com/show_bug.cgi?id=1047577

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 173c291473)

Conflicts:
	src/rpc/virnetserverclient.c - older locking style
This commit is contained in:
Jiri Denemark 2014-01-09 22:26:40 +01:00 committed by Guido Günther
parent 2786686eb5
commit ffdb640963
1 changed files with 14 additions and 1 deletions
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15
src/rpc/virnetserverclient.c
View File

@ -1217,9 +1217,22 @@ cleanup:
int
virNetServerClientStartKeepAlive(virNetServerClientPtr client)
{
int ret;
int ret = -1;
virNetServerClientLock(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:
virNetServerClientUnlock(client);
return ret;
}