diff options
| author | Julian Anastasov <ja@ssi.bg> | 2015-06-16 22:56:39 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-21 09:43:40 -0700 |
| commit | 2c51a97f76d20ebf1f50fef908b986cb051fdff9 (patch) | |
| tree | db087ec45b63ad4d7b1530ac01d4bb37f5148b2f /net/core | |
| parent | f98f4514d07871da7a113dd9e3e330743fd70ae4 (diff) | |
| download | linux-2c51a97f76d20ebf1f50fef908b986cb051fdff9.tar.bz2 | |
neigh: do not modify unlinked entries
The lockless lookups can return entry that is unlinked.
Sometimes they get reference before last neigh_cleanup_and_release,
sometimes they do not need reference. Later, any
modification attempts may result in the following problems:
1. entry is not destroyed immediately because neigh_update
can start the timer for dead entry, eg. on change to NUD_REACHABLE
state. As result, entry lives for some time but is invisible
and out of control.
2. __neigh_event_send can run in parallel with neigh_destroy
while refcnt=0 but if timer is started and expired refcnt can
reach 0 for second time leading to second neigh_destroy and
possible crash.
Thanks to Eric Dumazet and Ying Xue for their work and analyze
on the __neigh_event_send change.
Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour")
Fixes: a263b3093641 ("ipv4: Make neigh lookups directly in output packet path.")
Fixes: 6fd6ce2056de ("ipv6: Do not depend on rt->n in ip6_finish_output2().")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/neighbour.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 3de654256028..2237c1b3cdd2 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -957,6 +957,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) rc = 0; if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE)) goto out_unlock_bh; + if (neigh->dead) + goto out_dead; if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) { if (NEIGH_VAR(neigh->parms, MCAST_PROBES) + @@ -1013,6 +1015,13 @@ out_unlock_bh: write_unlock(&neigh->lock); local_bh_enable(); return rc; + +out_dead: + if (neigh->nud_state & NUD_STALE) + goto out_unlock_bh; + write_unlock_bh(&neigh->lock); + kfree_skb(skb); + return 1; } EXPORT_SYMBOL(__neigh_event_send); @@ -1076,6 +1085,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, if (!(flags & NEIGH_UPDATE_F_ADMIN) && (old & (NUD_NOARP | NUD_PERMANENT))) goto out; + if (neigh->dead) + goto out; if (!(new & NUD_VALID)) { neigh_del_timer(neigh); @@ -1225,6 +1236,8 @@ EXPORT_SYMBOL(neigh_update); */ void __neigh_set_probe_once(struct neighbour *neigh) { + if (neigh->dead) + return; neigh->updated = jiffies; if (!(neigh->nud_state & NUD_FAILED)) return; |