dccp: fix undefined behavior with 'cwnd' shift in ccid2_cwnd_restart()

[linux-2.6-microblaze.git] / net / dccp / ccids / ccid2.c

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 2b75df4..842a9c7 100644 (file)
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -229,14 +229,16 @@ static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
        struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
        u32 cwnd = hc->tx_cwnd, restart_cwnd,
            iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache);
+       s32 delta = now - hc->tx_lsndtime;
 
        hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2));
 
        /* don't reduce cwnd below the initial window (IW) */
        restart_cwnd = min(cwnd, iwnd);
-       cwnd >>= (now - hc->tx_lsndtime) / hc->tx_rto;
-       hc->tx_cwnd = max(cwnd, restart_cwnd);
 
+       while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd)
+               cwnd >>= 1;
+       hc->tx_cwnd = max(cwnd, restart_cwnd);
        hc->tx_cwnd_stamp = now;
        hc->tx_cwnd_used  = 0;