[PATCH 2/2] tcp: account for ts offset only if tsecr not zero

[Alexey Kodanev]

We can get SYN with zero tsecr, don't apply offset in this case.

Fixes: ee684b6f2830 ("tcp: send packets with a socket timestamp")
Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com>
---
 net/ipv4/tcp_minisocks.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 28ce5ee..baff824 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -106,7 +106,8 @@ enum tcp_tw_status
                tcp_parse_options(skb, &tmp_opt, 0, NULL);
 
                if (tmp_opt.saw_tstamp) {
-                       tmp_opt.rcv_tsecr       -= tcptw->tw_ts_offset;
+                       if (tmp_opt.rcv_tsecr)
+                               tmp_opt.rcv_tsecr -= tcptw->tw_ts_offset;
                        tmp_opt.ts_recent       = tcptw->tw_ts_recent;
                        tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
                        paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
-- 
1.7.1