dccp_diag: LISTEN sockets don't have CCIDs

And thus when we try to use 'ss -danemi' on these sockets that have no
ccid blocks (data collected using systemtap after I fixed the problem):

dccp_diag_get_info sk=0xffff8801220a3100, dp->dccps_hc_rx_ccid=0x0000000000000000, dp->dccps_hc_tx_ccid=0x0000000000000000

We get an OOPS:

mica.ghostprotocols.net login: BUG: unable to handle kernel NULL pointer
dereferenc0
IP: [<ffffffffa0136082>] dccp_diag_get_info+0x82/0xc0 [dccp_diag]
PGD 12106f067 PUD 122488067 PMD 0
Oops: 0000 [#1] PREEMPT

Fix is trivial, and 'ss -d' is working again:

[root@mica ~]# ss -danemi
State   Recv-Q Send-Q   Local Address:Port   Peer Address:Port
LISTEN  0      0                    *:5001              *:*
ino:7288 sk:220a3100ffff8801
	 mem:(r0,w0,f0,t0) cwnd:0 ssthresh:0
[root@mica ~]#

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dccp/diag.c b/net/dccp/diag.c
index 652a1b67f727dc6fce90eeff772e70d53c209c47..b21f261da75ee2572e40ce44f44746c3ee899e7a 100644 (file)
--- a/net/dccp/diag.c
+++ b/net/dccp/diag.c
@@ -32,8 +32,11 @@ static void dccp_get_info(struct sock *sk, struct tcp_info *info)
        if (dp->dccps_hc_rx_ackvec != NULL)
                info->tcpi_options |= TCPI_OPT_SACK;
 
-       ccid_hc_rx_get_info(dp->dccps_hc_rx_ccid, sk, info);
-       ccid_hc_tx_get_info(dp->dccps_hc_tx_ccid, sk, info);
+       if (dp->dccps_hc_rx_ccid != NULL)
+               ccid_hc_rx_get_info(dp->dccps_hc_rx_ccid, sk, info);
+
+       if (dp->dccps_hc_tx_ccid != NULL)
+               ccid_hc_tx_get_info(dp->dccps_hc_tx_ccid, sk, info);
 }
 
 static void dccp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,