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Groups > linux.kernel > #1691551

[PATCH 3.18 01/28] ipv6: avoid unregistering inet6_dev for loopback

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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/ipv6/addrconf.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2829,6 +2829,7 @@ static int addrconf_notify(struct notifi
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct inet6_dev *idev = __in6_dev_get(dev);
+	struct net *net = dev_net(dev);
 	int run_pending = 0;
 	int err;
 
@@ -2925,7 +2926,7 @@ 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;
 

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[PATCH 3.18 00/28] 3.18.62-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 22/28] crypto: atmel - only treat EBUSY as transient if backlog Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 25/28] sched/topology: Optimize build_group_mask() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 16/28] fs/dcache.c: fix spin lockup issue on nlru->lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 19/28] vt: fix unchecked __put_user() in tioclinux ioctls Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 12/28] parisc: DMA API: return error instead of BUG_ON for dma ops on non dma devs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:20 +0200
  [PATCH 3.18 08/28] cfg80211: Check if PMKID attribute is of expected size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 09/28] irqchip/gic-v3: Fix out-of-bound access in gic_set_affinity Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 03/28] net: prevent sign extension in dev_get_stats() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 14/28] tools/lib/lockdep: Reduce MAX_LOCK_DEPTH to avoid overflowing lock_chain/: Depth Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 23/28] crypto: sha1-ssse3 - Disable avx2 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 07/28] cfg80211: Validate frequencies nested in NL80211_ATTR_SCAN_FREQUENCIES Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 01/28] ipv6: avoid unregistering inet6_dev for loopback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 04/28] ipv6: dad: dont remove dynamic addresses if link is down Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  [PATCH 3.18 11/28] parisc: use compat_sys_keyctl() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-19 13:30 +0200
  Re: [PATCH 3.18 00/28] 3.18.62-stable review Guenter Roeck <linux@roeck-us.net> - 2017-07-19 22:40 +0200
  Re: [PATCH 3.18 00/28] 3.18.62-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-07-20 01:50 +0200
    Re: [PATCH 3.18 00/28] 3.18.62-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-20 07:10 +0200

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