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ipv6: blackhole_netdev needs snmp6 counters 

Whenever rt6_uncached_list_flush_dev() swaps rt->rt6_idev
to the blackhole device, parts of IPv6 stack might still need
to increment one SNMP counter.

Root cause, patch from Ido, changelog from Eric :)

This bug suggests that we need to audit rt->rt6_idev usages
and make sure they are properly using RCU protection.

Fixes: e5f80fcf86 ("ipv6: give an IPv6 dev to blackhole_netdev")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ido Schimmel 2022-02-13 18:10:56 -08:00 committed by David S. Miller
parent 7db45f8d95
commit dd263a8cb1
1 changed files with 9 additions and 9 deletions
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18
net/ipv6/addrconf.c
View File

@ -400,16 +400,16 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
/* We refer to the device */ /* We refer to the device */
dev_hold_track(dev, &ndev->dev_tracker, GFP_KERNEL); dev_hold_track(dev, &ndev->dev_tracker, GFP_KERNEL);
if (dev != blackhole_netdev) { if (snmp6_alloc_dev(ndev) < 0) {
if (snmp6_alloc_dev(ndev) < 0) { netdev_dbg(dev, "%s: cannot allocate memory for statistics\n",
netdev_dbg(dev, "%s: cannot allocate memory for statistics\n", __func__);
__func__); neigh_parms_release(&nd_tbl, ndev->nd_parms);
neigh_parms_release(&nd_tbl, ndev->nd_parms); dev_put_track(dev, &ndev->dev_tracker);
dev_put_track(dev, &ndev->dev_tracker); kfree(ndev);
kfree(ndev); return ERR_PTR(err);
return ERR_PTR(err); }
}
if (dev != blackhole_netdev) {
if (snmp6_register_dev(ndev) < 0) { if (snmp6_register_dev(ndev) < 0) {
netdev_dbg(dev, "%s: cannot create /proc/net/dev_snmp6/%s\n", netdev_dbg(dev, "%s: cannot create /proc/net/dev_snmp6/%s\n",
__func__, dev->name); __func__, dev->name);