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Prevent premature shrinking of the scaled receive window

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which can cause a TCP client to use invalid or stale TCP sequence numbers for ACK packets.

Packets with old sequence numbers are ignored and not used to update the send window size.
This might cause the TCP session to hang indefinitely under some circumstances.

Reported by:	Cui Cheng
Reviewed by:	tuexen (mentor), rgrimes (mentor)
Approved by:	tuexen (mentor), rgrimes (mentor)
MFC after:	3 weeks
Sponsored by:	NetApp, Inc.
Differential Revision:	https://reviews.freebsd.org/D24515
This commit is contained in:
rscheff 2020-04-29 22:01:33 +00:00
parent 57588206fe
commit 9ff3e71cd0
3 changed files with 12 additions and 3 deletions
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5
sys/netinet/tcp_output.c
View File

@ -1238,8 +1238,11 @@ tcp_output(struct tcpcb *tp)
if (flags & TH_SYN)
th->th_win = htons((u_short)
(min(sbspace(&so->so_rcv), TCP_MAXWIN)));
else
else {
/* Avoid shrinking window with window scaling. */
recwin = roundup2(recwin, 1 << tp->rcv_scale);
th->th_win = htons((u_short)(recwin >> tp->rcv_scale));
}
/*
* Adjust the RXWIN0SENT flag - indicate that we have advertised

5
sys/netinet/tcp_stacks/bbr.c
View File

@ -13756,8 +13756,11 @@ bbr_output_wtime(struct tcpcb *tp, const struct timeval *tv)
if (flags & TH_SYN)
th->th_win = htons((u_short)
(min(sbspace(&so->so_rcv), TCP_MAXWIN)));
else
else {
/* Avoid shrinking window with window scaling. */
recwin = roundup2(recwin, 1 << tp->rcv_scale);
th->th_win = htons((u_short)(recwin >> tp->rcv_scale));
}
/*
* Adjust the RXWIN0SENT flag - indicate that we have advertised a 0
* window. This may cause the remote transmitter to stall. This

5
sys/netinet/tcp_stacks/rack.c
View File

@ -9572,8 +9572,11 @@ rack_output(struct tcpcb *tp)
if (flags & TH_SYN)
th->th_win = htons((u_short)
(min(sbspace(&so->so_rcv), TCP_MAXWIN)));
else
else {
/* Avoid shrinking window with window scaling. */
recwin = roundup2(recwin, 1 << tp->rcv_scale);
th->th_win = htons((u_short)(recwin >> tp->rcv_scale));
}
/*
* Adjust the RXWIN0SENT flag - indicate that we have advertised a 0
* window. This may cause the remote transmitter to stall. This