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csm-xsmp-server.c: fix a use-after-free when an XSMP client fails during setup #220

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csm-xsmp-server.c: fix a use-after-free when an XSMP client fails during setup #220

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46 changes: 33 additions & 13 deletions cinnamon-session/csm-xsmp-server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,8 @@ typedef struct {
typedef struct {
guint watch_id;
guint protocol_timeout;
/* Set once a CsmXSMPClient owns the connection */
gboolean handed_over;
} CsmIceConnectionWatch;

static void
Expand Down Expand Up @@ -128,6 +130,7 @@ ice_protocol_timeout (IceConn ice_conn)
ice_conn, IceConnectionStatus (ice_conn));

data = ice_conn->context;
ice_conn->context = NULL;

free_ice_connection_watch (data);
disconnect_ice_connection (ice_conn);
Expand All @@ -143,15 +146,26 @@ auth_iochannel_watch (GIOChannel *source,

CsmIceConnectionWatch *data;
gboolean keep_going;
IceProcessMessagesStatus status;

data = ice_conn->context;

switch (IceProcessMessages (ice_conn, NULL, NULL)) {
status = IceProcessMessages (ice_conn, NULL, NULL);

if (data->handed_over) {
/* The sources were removed by accept_xsmp_connection(), and
* the CsmXSMPClient owns the connection now. */
g_free (data);
return FALSE;
}

switch (status) {
case IceProcessMessagesSuccess:
keep_going = TRUE;
break;
case IceProcessMessagesIOError:
g_debug ("CsmXsmpServer: IceProcessMessages returned IceProcessMessagesIOError");
ice_conn->context = NULL;
free_ice_connection_watch (data);
disconnect_ice_connection (ice_conn);
keep_going = FALSE;
Expand Down Expand Up @@ -344,8 +358,25 @@ accept_xsmp_connection (SmsConn sms_conn,
ice_conn = SmsGetIceConnection (sms_conn);
data = ice_conn->context;

if (data == NULL) {
/* Already handed over to a CsmXSMPClient. */
g_debug ("CsmXsmpServer: connection already handed over, rejecting");

*failure_reason_ret = strdup ("Refusing a second client setup on the same connection\n");
return FALSE;
}

/* Each CsmXSMPClient has its own IceConn watcher */
free_ice_connection_watch (data);
if (data->watch_id) {
g_source_remove (data->watch_id);
data->watch_id = 0;
}
if (data->protocol_timeout) {
g_source_remove (data->protocol_timeout);
data->protocol_timeout = 0;
}
data->handed_over = TRUE;
ice_conn->context = NULL;

client = csm_xsmp_client_new (ice_conn);

Expand All @@ -370,17 +401,6 @@ ice_error_handler (IceConn conn,
g_debug ("CsmXsmpServer: ice_error_handler (%p, %s, %d, %lx, %d, %d)",
conn, swap ? "TRUE" : "FALSE", offending_minor_opcode,
offending_sequence, error_class, severity);

if (severity == IceCanContinue) {
return;
}

/* FIXME: the ICElib docs are completely vague about what we're
* supposed to do in this case. Need to verify that calling
* IceCloseConnection() here is guaranteed to cause neither
* free-memory-reads nor leaks.
*/
IceCloseConnection (conn);
}

static void
Expand Down