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ipv4: fib: Fix NULL pointer deref during fib_sync_down_dev()

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Michał reported a NULL pointer deref during fib_sync_down_dev() when
unregistering a netdevice. The problem is that we don't check for
'in_dev' being NULL, which can happen in very specific cases.

Usually routes are flushed upon NETDEV_DOWN sent in either the netdev or
the inetaddr notification chains. However, if an interface isn't
configured with any IP address, then it's possible for host routes to be
flushed following NETDEV_UNREGISTER, after NULLing dev->ip_ptr in
inetdev_destroy().

To reproduce:
$ ip link add type dummy
$ ip route add local 1.1.1.0/24 dev dummy0
$ ip link del dev dummy0

Fix this by checking for the presence of 'in_dev' before referencing it.

Fixes: 982acb9756 ("ipv4: fib: Notify about nexthop status changes")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ido Schimmel 2017-07-28 23:27:44 +03:00 committed by David S. Miller
parent 7ad813f208
commit 71ed7ee35a
1 changed files with 1 additions and 1 deletions
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2
net/ipv4/fib_semantics.c
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@ -1452,7 +1452,7 @@ static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
&info.info);
case FIB_EVENT_NH_DEL:
if ((IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
if ((in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
(fib_nh->nh_flags & RTNH_F_DEAD))
return call_fib_notifiers(dev_net(fib_nh->nh_dev),