netdev - neigh_params_release() usage in net/ipv6/addrconf.c

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <8A0B031A-1483-49FD-A4AD-CA4EA87E9359@gmail.com>
Date:	Fri, 15 May 2009 12:33:39 -0400
From:	Chase Douglas <chasedouglas.lists@...il.com>
To:	netdev@...r.kernel.org
Subject: neigh_params_release() usage in net/ipv6/addrconf.c

I'm debugging an issue I'm seeing when I use vlan with IPv6 support.  
After bringing up the device, I'm unable to bring it down and  
unregister it. I put some debug statements around dev_hold() and  
dev_put() to see what was going on:

dev_hold() called on lo.2, new refcnt: 1 (net/core/dev.c:4162)
dev_hold() called on lo.2, new refcnt: 2 (net/core/neighbour.c:1357)
dev_hold() called on lo.2, new refcnt: 3 (net/ipv4/devinet.c:178)
dev_hold() called on lo.2, new refcnt: 4 (net/core/neighbour.c:1357)
dev_hold() called on lo.2, new refcnt: 5 (net/8021q/vlan.c:266)
dev_hold() called on lo.2, new refcnt: 6 (net/core/link_watch.c:219)
dev_put()  called on lo.2, new refcnt: 5 (net/core/link_watch.c:191)
dev_hold() called on lo.2, new refcnt: 6 (net/core/dev.c:684)
dev_put()  called on lo.2, new refcnt: 5 (net/ipv4/fib_semantics.c:149)
dev_hold() called on lo.2, new refcnt: 6 (net/core/dev.c:684)
dev_hold() called on lo.2, new refcnt: 7 (net/ipv4/fib_frontend.c:173)
dev_put()  called on lo.2, new refcnt: 6 (net/ipv4/route.c:2453)
dev_put()  called on lo.2, new refcnt: 5 (net/ipv4/fib_semantics.c:149)
dev_put()  called on lo.2, new refcnt: 4 (net/core/neighbour.c:1393)
dev_put()  called on lo.2, new refcnt: 3 (net/ipv4/devinet.c:151)
dev_put()  called on lo.2, new refcnt: 2 (net/core/dev.c:4010)
dev_put()  called on lo.2, new refcnt: 1 (net/8021q/vlan.c:182)
unregister_netdevice: waiting for lo.2 to become free. Usage count = 2

The fourth dev_hold() is in neigh_parms_alloc(), called by  
ipv6_add_dev(). The only place I see neigh_parms_release() called in  
addrconf.c is if ipv6_add_dev() fails later on, or when taking the  
device down in addrconf_ifdown(). Unfortunately, when I bring the vlan  
dev down I never see addrconf_ifdown() called with the how parameter  
set to 1, which is the only instance where neigh_parms_release() would  
be called.

Why is neigh_parms_release() called in addrconf_ifdown() instead of  
in6_dev_finish_destroy(), which looks to me to be the complement of  
ipv6_add_dev()? If neigh_parms_release() really should be called in  
addrconf_ifdown(), does anyone know why it's not being called properly  
in this instance?

PS: I am running my tests using a slightly modified SLES 11 kernel. I  
haven't been able to find anything in the git trees that would  
indicate to me that the problem has been fixed upstream.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html