Date: Sun, 11 Aug 2002 10:33:12 -0700 (PDT) From: "G.P. de Boer" <g.p.de.boer@st.hanze.nl> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/41552: TCP timers' sysctl's overflow Message-ID: <200208111733.g7BHXCRb061465@www.freebsd.org>
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>Number: 41552 >Category: kern >Synopsis: TCP timers' sysctl's overflow >Confidential: no >Severity: serious >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun Aug 11 10:40:01 PDT 2002 >Closed-Date: >Last-Modified: >Originator: G.P. de Boer >Release: 4.6.1-RELEASE-p10 >Organization: none >Environment: FreeBSD stranraer 4.6.1-RELEASE-p10 FreeBSD 4.6.1-RELEASE-p10 #4: Sun Aug 11 16:06:11 CEST 2002 root@stranraer:/usr/obj/usr/src/sys/KERNEL-12-06-2002 i386 >Description: When setting syscontrols like net.inet.tcp.keepidle on a system with clocktick-granularity above 1000 Hz, there's an overflow triggered, resulting in at least inaccurate, but sometimes negative TCP timeouts. This could result in a situation where keep-alive isn't working as expected or at all, which could then be exploited to DoS a host. >How-To-Repeat: root@stranraer:~$ sysctl -w net.inet.tcp.keepidle=7200000 net.inet.tcp.keepidle: 720000 -> 757549 On systems with clocktick-granularity >1000. >Fix: As already merged into RELENG_4: http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/tcp_timer.c?r1=1.34.2.12 >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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