Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Sat, 09 Sep 2017 22:47:39 +0100 | Subject | [PATCH 3.2 091/106] ipv6: avoid unregistering inet6_dev for loopback |
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3.2.93-rc1 review patch. If anyone has any objections, please let me know.
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From: WANG Cong <xiyou.wangcong@gmail.com>
commit 60abc0be96e00ca71bac083215ac91ad2e575096 upstream.
The per netns loopback_dev->ip6_ptr is unregistered and set to NULL when its mtu is set to smaller than IPV6_MIN_MTU, this leads to that we could set rt->rt6i_idev NULL after a rt6_uncached_list_flush_dev() and then crash after another call.
In this case we should just bring its inet6_dev down, rather than unregistering it, at least prior to commit 176c39af29bc ("netns: fix addrconf_ifdown kernel panic") we always override the case for loopback.
Thanks a lot to Andrey for finding a reliable reproducer.
Fixes: 176c39af29bc ("netns: fix addrconf_ifdown kernel panic") Reported-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Daniel Lezcano <dlezcano@fr.ibm.com> Cc: David Ahern <dsahern@gmail.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: David Ahern <dsahern@gmail.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: the NETDEV_CHANGEMTU case used to fall-through to the NETDEV_DOWN case here, so replace that with a separate call to addrconf_ifdown()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2633,6 +2633,7 @@ static int addrconf_notify(struct notifi { struct net_device *dev = (struct net_device *) data; struct inet6_dev *idev = __in6_dev_get(dev); + struct net *net = dev_net(dev); int run_pending = 0; int err; @@ -2733,7 +2734,7 @@ static int addrconf_notify(struct notifi * IPV6_MIN_MTU stop IPv6 on this interface. */ if (dev->mtu < IPV6_MIN_MTU) - addrconf_ifdown(dev, 1); + addrconf_ifdown(dev, dev != net->loopback_dev); } break; @@ -2754,6 +2755,8 @@ static int addrconf_notify(struct notifi * MTU falled under IPV6_MIN_MTU. * Stop IPv6 on this interface. */ + addrconf_ifdown(dev, dev != net->loopback_dev); + break; case NETDEV_DOWN: case NETDEV_UNREGISTER:
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