Date: Thu, 22 Mar 2001 16:50:53 +0000 From: thinker <thinker@branda.to> To: FreeBSD-gnats-submit@freebsd.org Subject: kern/25986: Socket would hang at LAST_ACK forever. Message-ID: <20010322165052.A46012@hell.branda.to> In-Reply-To: <courier.3ABA2BFA.0000B3A7@hell.branda.to>; from on Thu, Mar 22, 2001 at 04:44:42PM %2B0000 References: <courier.3ABA2BFA.0000B3A7@hell.branda.to>
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>Number: 25986
>Category: kern
>Synopsis: Socket would hang at LAST_ACK forever.
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Thu Mar 22 00:50:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: thinker
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD hell.branda.to 5.0-CURRENT FreeBSD 5.0-CURRENT #1: Wed Mar 7 20:41:54 GMT 2001 thinker@hell.branda.to:/usr/src/sys/compile/thk i386
>Description:
When TCP socket goes to LAST_ACK state & remote host do not respone
ACK forever, socket would stay at LAST_ACK forever and never be removed.
It would be a bug expolit by DDoS attacker. Patch file to fix the problem
is following.
>How-To-Repeat:
>Fix:
--- sys/netinet/tcp_usrreq.c.orig Thu Mar 22 14:59:45 2001
+++ sys/netinet/tcp_usrreq.c Thu Mar 22 15:04:49 2001
@@ -1139,13 +1139,15 @@
tp->t_state = TCPS_LAST_ACK;
break;
}
- if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
+ if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
soisdisconnected(tp->t_inpcb->inp_socket);
- /* To prevent the connection hanging in FIN_WAIT_2 forever. */
- if (tp->t_state == TCPS_FIN_WAIT_2)
- callout_reset(tp->tt_2msl, tcp_maxidle,
- tcp_timer_2msl, tp);
- }
+ /*
+ * To prevent the connection hanging in FIN_WAIT_2 &
+ * TCPS_LAST_ACK forever.
+ */
+ if (tp->t_state == TCPS_FIN_WAIT_2 || tp->t_state == TCPS_LAST_ACK)
+ callout_reset(tp->tt_2msl, tcp_maxidle,
+ tcp_timer_2msl, tp);
return (tp);
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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