Date: Wed, 30 May 2007 18:38:37 GMT From: Christos Dionissopoulos<chdio@debug.gr> To: freebsd-gnats-submit@FreeBSD.org Subject: i386/113170: if_bridge span produces kernel panic Message-ID: <200705301838.l4UIcbRx024340@www.freebsd.org> Resent-Message-ID: <200705301840.l4UIe4L0015263@freefall.freebsd.org>
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>Number: 113170
>Category: i386
>Synopsis: if_bridge span produces kernel panic
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-i386
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed May 30 18:40:04 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator: Christos Dionissopoulos
>Release: Current-7
>Organization:
>Environment:
FreeBSD mail.debug.gr 7.0-CURRENT FreeBSD 7.0-CURRENT #2: Tue May 7 11:53:05 EEST 2007 root@mail.debug.gr:/usr/obj/usr/src/sys/DEV7 i386
>Description:
Trying to make clean-layer2 traffic (STP/CDP) to flow from one switch to another (unidirectional), I figure out that if_bridge(4) filters pure-layer2 frames (non-IP), unless you use a span port on a single-port "bridge".
But, when I create a if_bridge(4) interface with 2 ethernet ports configured as follows:
- NIC1, as a normal attached bridging port, and
- NIC2, as a span port
this results a kernel panic.
If I run a kernel with debuging options enabled, I see a KASSERT that describes the "panic" as shown in /usr/src/sys/net/if_bridge.c line:2757
/* we may return with the IP fields swapped, ensure its not shared */
KASSERT(M_WRITABLE(*mp), ("%s: modifying a shared mbuf", __func__));
any ideas/patch are welcome.
>How-To-Repeat:
ifconfig bridge0 create
ifconfig bridge0 addm em0 span em1
ifconfig em0 up
ifconfig em1 up
ifconfig bridge0 up
just wait for some traffic (layer2-only included, like STP/CDP) to flow thru interfaces and KASSERT error message appears with kernel panic.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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