Date: Tue, 27 Feb 2001 12:26:50 -0800 (PST) From: msmith@netapp.com To: freebsd-gnats-submit@FreeBSD.org Subject: kern/25421: route structures are being leaked. Message-ID: <200102272026.f1RKQoS35094@freefall.freebsd.org>
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>Number: 25421
>Category: kern
>Synopsis: route structures are being leaked.
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Feb 27 12:30:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Mark Smith
>Release: 4.2
>Organization:
Network Appliance
>Environment:
>Description:
This was found in a kernel with networking code derived from FreeBSD
not from FreeBSD itself. However, from a code review of the FreeBSD-4.2 source, it appears FreeBSD has the same problem.
In in_losing() we have this:
if ((rt = inp->inp_route.ro_rt)) {
inp->inp_route.ro_rt = 0;
bzero((caddr_t)&info, sizeof(info));
info.rti_info[RTAX_DST] =
(struct sockaddr *)&inp->inp_route.ro_dst;
info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
info.rti_info[RTAX_NETMASK] = rt_mask(rt);
rt_missmsg(RTM_LOSING, &info, rt->rt_flags, 0);
if (rt->rt_flags & RTF_DYNAMIC)
(void) rtrequest(RTM_DELETE, rt_key(rt),
rt->rt_gateway, rt_mask(rt), rt->rt_flags,
(struct rtentry **)0);
else
/*
* A new route can be allocated
* the next time output is attempted.
*/
rtfree(rt);
}
Since rt was the cached route of the pcb, the ref count is >= 1 since
the pcb will have a ref count on it. In the case of a dynamic route,
in_losing calls rtrequest to delete the route but not rtfree.
rtrequest() only deletes the route from the routing table. It does
not free the route structure unless rt_refcnt is 0. We know
it won't be zero because the pcb has a ref count. As a result it
appears that we leak a route structure since it will never be freed.
>How-To-Repeat:
The problem is easiest to recreate on a lossy network where we
receive a lot of route redirects.
>Fix:
In in_losing() the fix appears to be to simply delete the else just
before the rtfree() call so that rtfree is always called.
>Release-Note:
>Audit-Trail:
>Unformatted:
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