[DCCP] getsockopt: Fix DCCP_SOCKOPT_[SEND,RECV]_CSCOV

We were only checking if there was enough space to put the int, but
left len as specified by the (malicious) user, sigh, fix it by setting
len to sizeof(val) and transfering just one int worth of data, the one
asked for.

Also check for negative len values.

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

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index cf28c53a389a24b49c82ccc21721139bcbf110e1..6607b7b14f34fde9a2324f28d90a8f2555cb5fcd 100644 (file)
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -575,7 +575,7 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
        if (get_user(len, optlen))
                return -EFAULT;
 
-       if (len < sizeof(int))
+       if (len < (int)sizeof(int))
                return -EINVAL;
 
        dp = dccp_sk(sk);
@@ -589,9 +589,11 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
                                               (__be32 __user *)optval, optlen);
        case DCCP_SOCKOPT_SEND_CSCOV:
                val = dp->dccps_pcslen;
+               len = sizeof(val);
                break;
        case DCCP_SOCKOPT_RECV_CSCOV:
                val = dp->dccps_pcrlen;
+               len = sizeof(val);
                break;
        case 128 ... 191:
                return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,