Commit 71ed7ee3 authored by Ido Schimmel's avatar Ido Schimmel Committed by David S. Miller

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

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: 982acb97 ("ipv4: fib: Notify about nexthop status changes")
Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
Reported-by: default avatarMichał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: default avatarMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7ad813f2
...@@ -1452,7 +1452,7 @@ static int call_fib_nh_notifiers(struct fib_nh *fib_nh, ...@@ -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, return call_fib_notifiers(dev_net(fib_nh->nh_dev), event_type,
&info.info); &info.info);
case FIB_EVENT_NH_DEL: 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_LINKDOWN) ||
(fib_nh->nh_flags & RTNH_F_DEAD)) (fib_nh->nh_flags & RTNH_F_DEAD))
return call_fib_notifiers(dev_net(fib_nh->nh_dev), return call_fib_notifiers(dev_net(fib_nh->nh_dev),
......
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