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 <andreyk...@google.com>
Cc: Andrey Konovalov <andreyk...@google.com>
Cc: Daniel Lezcano <dlezc...@fr.ibm.com>
Cc: David Ahern <dsah...@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
net/ipv6/addrconf.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 686c923..1d2dbac 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3369,6 +3369,7 @@ static int addrconf_notify(struct notifier_block *this,
unsigned long event,
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct netdev_notifier_changeupper_info *info;
struct inet6_dev *idev = __in6_dev_get(dev);
+ struct net *net = dev_net(dev);
int run_pending = 0;
int err;
@@ -3384,7 +3385,7 @@ static int addrconf_notify(struct notifier_block *this,
unsigned long event,
case NETDEV_CHANGEMTU:
/* if MTU under 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;
}
@@ -3500,7 +3501,7 @@ static int addrconf_notify(struct notifier_block *this,
unsigned long event,
* 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;
--
2.5.5
