Date: Thu, 22 Mar 2001 01:10:02 -0800 (PST) From: David Xu <bsddiy@21cn.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/25986: Socket would hang at LAST_ACK forever. Message-ID: <200103220910.f2M9A2321153@freefall.freebsd.org>
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The following reply was made to PR kern/25986; it has been noted by GNATS.
From: David Xu <bsddiy@21cn.com>
To: thinker <thinker@branda.to>
Cc: FreeBSD-gnats-submit@freebsd.org
Subject: Re: kern/25986: Socket would hang at LAST_ACK forever.
Date: Thu, 22 Mar 2001 17:15:37 +0800
Hello thinker,
Friday, March 23, 2001, 12:50:53 AM, you wrote:
>>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:
t> 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:
t> When TCP socket goes to LAST_ACK state & remote host do not respone
t> ACK forever, socket would stay at LAST_ACK forever and never be removed.
t> It would be a bug expolit by DDoS attacker. Patch file to fix the problem
t> is following.
>>How-To-Repeat:
>>Fix:
t> --- sys/netinet/tcp_usrreq.c.orig Thu Mar 22 14:59:45 2001
t> +++ sys/netinet/tcp_usrreq.c Thu Mar 22 15:04:49 2001
t> @@ -1139,13 +1139,15 @@
t> tp->t_state = TCPS_LAST_ACK;
t> break;
t> }
t> - if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
t> + if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
t> soisdisconnected(tp->t_inpcb->inp_socket);
t> - /* To prevent the connection hanging in FIN_WAIT_2 forever. */
t> - if (tp->t_state == TCPS_FIN_WAIT_2)
t> - callout_reset(tp->tt_2msl, tcp_maxidle,
t> - tcp_timer_2msl, tp);
t> - }
t> + /*
t> + * To prevent the connection hanging in FIN_WAIT_2 &
t> + * TCPS_LAST_ACK forever.
t> + */
+ if (tp->>t_state == TCPS_FIN_WAIT_2 || tp->t_state == TCPS_LAST_ACK)
t> + callout_reset(tp->tt_2msl, tcp_maxidle,
t> + tcp_timer_2msl, tp);
t> return (tp);
t> }
Thank you!
it's a long standing bug, but seems no one want to fix it, don't know why!
--
Best regards,
David Xu
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