[CCID2]: Fix sequence number arithmetic/comparisons

This replaces use of normal subtraction with modulo-48 subtraction.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 7 deletions

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 7873dc78b6bc..55522182f2fa 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -24,9 +24,6 @@
 
 /*
  * This implementation should follow RFC 4341
- *
- * BUGS:
- * - sequence number wrapping
  */
 
 #include "../ccid.h"
@@ -619,9 +616,8 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 /* go through this ack vector */
                 while (veclen--) {
                         const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
-                        u64 ackno_end_rl;
+                        u64 ackno_end_rl = SUB48(ackno, rl);
 
-                        dccp_set_seqno(&ackno_end_rl, ackno - rl);
                         ccid2_pr_debug("ackvec start:%llu end:%llu\n",
                                        (unsigned long long)ackno,
                                        (unsigned long long)ackno_end_rl);
@@ -671,8 +667,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                         if (done)
                                 break;
 
-
-                        dccp_set_seqno(&ackno, ackno_end_rl - 1);
+                        ackno = SUB48(ackno_end_rl, 1);
                         vector++;
                 }
                 if (done)