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Fix an issue I introuced in r367530: tcp_twcheck() can be called

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with to == NULL for SYN segments. So don't assume tp != NULL.
Thanks to jhb@ for reporting and suggesting a fix.

PR:			250499
MFC after:		1 week
XMFC-with:		r367530
Sponsored by:		Netflix, Inc.
This commit is contained in:
Michael Tuexen 2020-11-20 13:00:28 +00:00
parent 1b3cb4dc04
commit 47384244f9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=367891
1 changed files with 13 additions and 10 deletions
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23
sys/netinet/tcp_timewait.c
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@ -374,6 +374,7 @@ tcp_twstart(struct tcpcb *tp)
/*
* Returns 1 if the TIME_WAIT state was killed and we should start over,
* looking for a pcb in the listen state. Returns 0 otherwise.
* It be called with to == NULL only for pure SYN-segments.
*/
int
tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
@ -397,6 +398,8 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
goto drop;
thflags = th->th_flags;
KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN,
("tcp_twcheck: called without options on a non-SYN segment"));
/*
* NOTE: for FIN_WAIT_2 (to be added later),
@ -411,16 +414,6 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
if (thflags & TH_RST)
goto drop;
/*
* If timestamps were negotiated during SYN/ACK and a
* segment without a timestamp is received, silently drop
* the segment.
* See section 3.2 of RFC 7323.
*/
if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) {
goto drop;
}
#if 0
/* PAWS not needed at the moment */
/*
@ -455,6 +448,16 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
if ((thflags & TH_ACK) == 0)
goto drop;
/*
* If timestamps were negotiated during SYN/ACK and a
* segment without a timestamp is received, silently drop
* the segment.
* See section 3.2 of RFC 7323.
*/
if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) {
goto drop;
}
/*
* Reset the 2MSL timer if this is a duplicate FIN.
*/